Still no sure what I am doing wrong.. Hmm tried a dozen different incarnations. Thank you! Here is the whole code. I wanted to replace the return with the success message that was posted earlier Thank you in advance!

public class SubmitCaseController {     
    public Case c { get; set; }
    // public String acctNum { get; set; }
    public SelectOption[] caseTypes { get; set;}
    
    public List<Case> UserCaseList
    {
        get
        {
            return [Select CreatedDate, Status, Origin, ClosedDate, CaseNumber, Subject, Owner.alias
                    From Case
                    Where Contact.Email = :UserInfo.getUserEmail() AND Origin = 'SF' AND Status NOT IN ('Closed','Completed') ORDER BY CaseNumber DESC limit 10]; 
                
        }
    }
    public Attachment objAttachment { get; set; }
    public SubmitCaseController(ApexPages.StandardController controller) {
        c = new Case();
        this.caseTypes = new SelectOption[]{};
        this.caseTypes.add(new SelectOption('-', '-'));
        this.caseTypes.add(new SelectOption('Question','Question'));
        this.caseTypes.add(new SelectOption('Problem', 'Problem'));
        this.caseTypes.add(new SelectOption('Enhancement', 'Enhancement'));
        objAttachment = new Attachment();
   }
    
    public Contact userContact
    {
        get
        {
            
            Contact cnt = [SELECT Id FROM Contact WHERE Email = :c.SuppliedEmail LIMIT 1];
            if (cnt != null) return cnt;
            else return null;
        }
    }

    public PageReference submitCase() {
       // List<Account> accts = [SELECT Id FROM Account WHERE AccountNumber = :acctNum Limit 100];

        // if (accts.size() != 1) {
            //ApexPages.Message msg = new ApexPages.Message(ApexPages.Severity.FATAL, 'Invalid account number');
            //ApexPages.addMessage(msg);
            //return null;
      //  } else {
            try {
                if (c.Type == '-') 
                {
                     ApexPages.addmessage(new ApexPages.message(ApexPages.severity.FATAL,'Please Select a Type'));
                     return null;
                }

                // c.AccountId = accts.get(0).Id;  
                c.SuppliedEmail = UserInfo.getUserEmail();
                c.Origin = 'SF';
                //c.RecordTypeId = '012W00000000Xmb';
                c.RecordTypeId = '012000000004yTO';
                c.Product__c = 'Salesforce.com';
                c.OwnerId = '00500000007HkiF';
                c.No_Closed_Email__c = FALSE;
                if (c.Customer_Facing__c == TRUE) {
                c.Priority = 'High -2';
                } else {(c.Customer_Facing__c = FALSE);
                
                (c.Priority = 'Med - 3');
                 }
                
                // now look for an associated contact with the same email
                Contact cnt = userContact;
                if (cnt != null) c.ContactId = cnt.Id;
                
                // Specify DML options to ensure the assignment rules are executed
                // Database.DMLOptions dmlOpts = new Database.DMLOptions();
                // dmlOpts.assignmentRuleHeader.useDefaultRule = true;
                // c.setOptions(dmlOpts); 
                
                // Insert the case
                INSERT c;
                if (objAttachment.Body != null) {
                    // Insert attachment if exists
                      objAttachment.ParentId = c.Id;
                    insert objAttachment;
                }
                
                return new PageReference('https://na31.salesforce.com/apex/submitcasethankyou');
            } catch (Exception e) {
                ApexPages.addMessages(e);
                return null;
            }
        }
    }