For instance I have some object  let's say "territory" which is look up fro user object

When I'm creating different territories and assigning them one particular  user let's say "user 1"

How Can I then  see related list of territories on this user?

I would like to know are any ways to save my current page state when refreshing this page

In my particular  case i have bucket which refreshing every time when add new product to it via rerendered attribute. I would like to save this bucket state when page will be refreshed

When I'm using PageReference class to reference to another page it seems like on referenced page viewstate remains 

Public PageReference backToPage(){

        return new PageReference('/apex/gindex');
    }

Is any ways to reference it and reload it fully;

<apex:outputLink value="https://c.eu6.visual.force.com/apex/gindex" id="theLink">Back to shop</apex:outputLink>

Public PageReference backToPage(){

            return new PageReference('/apex/gindex');
        }

I' m passing parametrs ro controller from 2 palaces 
first look like:

<apex:dataTable id="tableCategories"  value="{!products}" var="prod" styleClass="table table-striped">      
.......
   <apex:column >
                        <apex:form >

                        <apex:commandButton action="{!makevisibleProduct}" value="View details" 
                         styleClass="btn-success">                
                                     <apex:param name="product" value="{!prod.name}"/>
                         </apex:commandButton>

                        </apex:form>

      </apex:column>

                     
controller:

public  with sharing class HomeController {
    private String  ProdName;
  public PageReference makevisibleProduct(){
          productVisibility=true;
            ProdName = ApexPages.currentPage().getParameters().get('product');
          return null;
    }
 public Boolean getisVisibleProduct(){
    
        return productVisibility;
    }

Then I want to render particualr product detail with name= Prodname;

Public Product__c getProduct(){
       
        List<Product__c> products =[Select name, description__c, quantity__c,price__c from Product__c
                                   WHERE name =: ProdName
                                   ];
        return products[0];
    }

Table that should displays products:

<apex:pageBlock id ="tableProduct" rendered="{!isVisibleProduct}" mode="maindetail">

                <vs:panel title="Demo Panel Primary" type="primary">
                    <table class="table table-condensed" >
                   
                    <tr>
                      <td class="active">{!product.name} </td>
                    </tr>
....

Whe clicking the button output is:

Visualforce Error
Help for this Page
System.ListException: List index out of bounds: 0 
Class.HomeController.getProduct: line 57, column 1

this line: 

return products[0];

But strangely thing that a has nearly the same button in another place of code which works fine:
 

      <apex:form >
                    <apex:repeat value="{!categories}" var="cat" id="theRepeat">

                        <apex:commandButton reRender="tableCategories" style="margin:4px" value="{!cat.name}"               styleClass="btn-success">

                            <apex:param name="category" value="{!cat.name}"/>
                            </apex:commandButton>

                    </apex:repeat>
         </apex:form>

<apex:dataTable id="tableCategories"  value="{!products}" var="prod" styleClass="table table-striped">
                    <apex:facet name="header">Products</apex:facet>
                    <apex:column value="{!prod.Category__r.name}" headerValue="Category name"/>
                    <apex:column value="{!prod.name}" headerValue="Product name"/>
.....

controller side
 

public List<Product__c> getProducts(){
        String CategoryName = ApexPages.currentPage().getParameters().get('category');

            List<Category__c> categs = [SELECT(select id, name, Category__r.name,Maker__r.name, description__c from product__r) from Category__c WHERE name = :CategoryName];
...
            products = categs[0].product__r;
            return products;

I would like to know are any ways to save my current page state when refreshing this page

In my particular  case i have bucket which refreshing every time when add new product to it via rerendered attribute. I would like to save this bucket state when page will be refreshed

When I'm using PageReference class to reference to another page it seems like on referenced page viewstate remains 

Public PageReference backToPage(){

        return new PageReference('/apex/gindex');
    }

Is any ways to reference it and reload it fully;

<apex:outputLink value="https://c.eu6.visual.force.com/apex/gindex" id="theLink">Back to shop</apex:outputLink>

Public PageReference backToPage(){

            return new PageReference('/apex/gindex');
        }

I' m passing parametrs ro controller from 2 palaces 
first look like:

<apex:dataTable id="tableCategories"  value="{!products}" var="prod" styleClass="table table-striped">      
.......
   <apex:column >
                        <apex:form >

                        <apex:commandButton action="{!makevisibleProduct}" value="View details" 
                         styleClass="btn-success">                
                                     <apex:param name="product" value="{!prod.name}"/>
                         </apex:commandButton>

                        </apex:form>

      </apex:column>

                     
controller:

public  with sharing class HomeController {
    private String  ProdName;
  public PageReference makevisibleProduct(){
          productVisibility=true;
            ProdName = ApexPages.currentPage().getParameters().get('product');
          return null;
    }
 public Boolean getisVisibleProduct(){
    
        return productVisibility;
    }

Then I want to render particualr product detail with name= Prodname;

Public Product__c getProduct(){
       
        List<Product__c> products =[Select name, description__c, quantity__c,price__c from Product__c
                                   WHERE name =: ProdName
                                   ];
        return products[0];
    }

Table that should displays products:

<apex:pageBlock id ="tableProduct" rendered="{!isVisibleProduct}" mode="maindetail">

                <vs:panel title="Demo Panel Primary" type="primary">
                    <table class="table table-condensed" >
                   
                    <tr>
                      <td class="active">{!product.name} </td>
                    </tr>
....

Whe clicking the button output is:

Visualforce Error
Help for this Page
System.ListException: List index out of bounds: 0 
Class.HomeController.getProduct: line 57, column 1

this line: 

return products[0];

But strangely thing that a has nearly the same button in another place of code which works fine:
 

      <apex:form >
                    <apex:repeat value="{!categories}" var="cat" id="theRepeat">

                        <apex:commandButton reRender="tableCategories" style="margin:4px" value="{!cat.name}"               styleClass="btn-success">

                            <apex:param name="category" value="{!cat.name}"/>
                            </apex:commandButton>

                    </apex:repeat>
         </apex:form>

<apex:dataTable id="tableCategories"  value="{!products}" var="prod" styleClass="table table-striped">
                    <apex:facet name="header">Products</apex:facet>
                    <apex:column value="{!prod.Category__r.name}" headerValue="Category name"/>
                    <apex:column value="{!prod.name}" headerValue="Product name"/>
.....

controller side
 

public List<Product__c> getProducts(){
        String CategoryName = ApexPages.currentPage().getParameters().get('category');

            List<Category__c> categs = [SELECT(select id, name, Category__r.name,Maker__r.name, description__c from product__r) from Category__c WHERE name = :CategoryName];
...
            products = categs[0].product__r;
            return products;