HELLO ALL,
THIS IS THE CUSTOM CODE WRITTEN TO FETCH THE HISTORY FOR ANY OBJECT IN SALESFORCE.
MODIFY IT AS PER NEED

public class yourClassForHistories
{
    public Id caseId {get; set;}
    public List<HistoryDetailClass> histories;
    // Variables
    public Static final Map<String, Schema.SObjectField> CaseFieldmap = Schema.SObjectType.Request__c.fields.getMap();
    public Static final List<Schema.PicklistEntry> fieldPicklistValues = Request__History.Field.getDescribe().getPicklistValues();

    public List<HistoryDetailClass> getHistories()
    {
        histories = new List<HistoryDetailClass>();
        List<Request__c> // Your Query
        
        list<Request__History>  // Your Query

        
        for(Request__History nowHistory : your List){
            GenericHistoryClass cHistory = new GenericHistoryClass();
            cHistory.createdById = nowHistory.CreatedBy.Id;
            cHistory.createdByName = nowHistory.CreatedBy.Name;
            cHistory.createdDate = nowHistory.CreatedDate;
            cHistory.field = nowHistory.Field;
            cHistory.id = nowHistory.Id;
            cHistory.newValue = String.valueOf(nowHistory.newValue);
            cHistory.oldValue = String.valueOf(nowHistory.oldValue);
            cHistory.parentId = nowHistory.ParentID;

            HistoryDetailClass tempHistory = new HistoryDetailClass();
            tempHistory = createHistoryEntry(cHistory);

            // Add to the list
            if(tempHistory != null){
                histories.add(tempHistory);
            }
        }

        histories.sort();
        return histories;
    }

    //Function to populate a temporary history record
    public HistoryDetailClass createHistoryEntry(GenericHistoryClass cHistory){
        HistoryDetailClass tempHistory = new HistoryDetailClass();
        String prevDate = '';

        if((cHistory.newValue == null && cHistory.oldValue == null)
                || (cHistory.newValue != null && !(string.valueOf(cHistory.newValue).startsWith('a0t') || string.valueOf(cHistory.newValue).startsWith('00G') ||
                    string.valueOf(cHistory.newValue).startsWith('005f') || string.valueOf(cHistory.newValue).startsWith('005e') ||
                    string.valueOf(cHistory.newValue).startsWith('005a')))
                || (cHistory.oldValue != null && !(string.valueOf(cHistory.oldValue).startsWith('a0t') || string.valueOf(cHistory.oldValue).startsWith('00G') ||
                    string.valueOf(cHistory.oldValue).startsWith('005f') || string.valueOf(cHistory.oldValue).startsWith('005e') ||
                    string.valueOf(cHistory.oldValue).startsWith('005a'))))
            {
                // Set the Date and who performed the action
                if(String.valueOf(cHistory.createdDate) != prevDate)
                {
                    tempHistory.theDate = String.valueOf(cHistory.createdDate);
                    tempHistory.who = cHistory.createdByName;
                    tempHistory.userId = cHistory.createdById;
                }
                else
                {
                    tempHistory.theDate = '';
                    tempHistory.who = '';
                    tempHistory.userId = cHistory.createdById;
                }
                prevDate = String.valueOf(cHistory.createdDate);

                // Get the field label
                String fieldLabel = YouClassForHistories.returnFieldLabel(cHistory.field);

                // Set the Action value
                if (String.valueOf(cHistory.field) == 'created')
                {
                    // on Creation
                    tempHistory.action = 'Created.';
                }
                else if(cHistory.oldValue != null && cHistory.newValue == null)
                {
                    // when deleting a value from a field
                    // Format the Date and if there's an error, catch it and re
                    try {
                        tempHistory.action = 'Deleted ' + Date.valueOf(cHistory.oldValue).format() + ' in <b>' + fieldLabel + '</b>.';
                    }
                    catch (Exception e)
                    {
                        tempHistory.action = 'Deleted ' + String.valueOf(cHistory.oldValue) + ' in <b>' + fieldLabel + '</b>.';
                    }
                }
                else
                {
                    // all other scenarios
                    String fromText = '';
                    if (cHistory.oldValue != null)
                    {
                        try {
                            fromText = ' from ' + Date.valueOf(cHistory.oldValue).format();
                        }
                        catch (Exception e)
                        {
                            fromText = ' from ' + String.valueOf(cHistory.oldValue);
                        }
                    }

                    String toText = '';
                    if (cHistory.NewValue != null)
                    {
                        try {
                            toText = Date.valueOf(cHistory.newValue).format();
                        }
                        catch (Exception e)
                        {
                            toText = String.valueOf(cHistory.newValue);
                        }
                    }

                    if(toText != '')
                        tempHistory.action = 'Changed <b>' + fieldLabel + '</b>' + fromText + ' to <b>' + toText + '</b>.';
                    else
                        tempHistory.action = 'Changed <b>' + fieldLabel;

                }

                String fieldValue=cHistory.field.replaceAll('__c','');
                fieldValue=fieldValue.replaceAll('_',' ');
                tempHistory.field=fieldValue;

            }

            return tempHistory;

    }

    // Function to return Field Label of a Case field given a Field API name
    public Static String returnFieldLabel(String fieldName)
    {
        if(yourClassForHistories.CaseFieldmap.containsKey(fieldName))
        return yourClassForHistories.CaseFieldmap.get(fieldName).getDescribe().getLabel();
        else
        {
            for(Schema.PicklistEntry pickList : fieldPicklistValues)
            {
                if(pickList.getValue() == fieldName)
                {
                    if(pickList.getLabel() != null){
                        return pickList.getLabel();
                    }
                    else{
                        return pickList.getValue();
                    }
                }
            }
        }
        return '';
    }


    // Inner Class to store the detail of the case history
    public class HistoryDetailClass implements Comparable{
        public String theDate {get; set;}
        public String who {get; set;}
        public Id userId {get; set;}
        public String action {get; set;}
        public String field{get; set;}
        public String OfferName{get; set;}

        public Integer compareTo(Object compareTo) {
            HistoryDetailClass compareToHistory = (HistoryDetailClass)compareTo;
            if (theDate == compareToHistory.theDate){
                return 0;
            }
            if (theDate > compareToHistory.theDate){
                return -1;
            }
            return 1;        
        }       
    }

    //Generic Inner Class that replecates the History Object
    public class GenericHistoryClass{
        public Id createdById {get;set;}
        public String createdByName {get;set;}
        public Datetime createdDate {get;set;}
        public String field {get;set;}
        public Id id {get;set;}
        public boolean isDeleted {get;set;}
        public String newValue {get;set;}
        public String oldValue {get;set;}
        public Id parentId {get;set;}
        public String offerName {get;set;}
    }

Thanks,
Rohit Alladi.

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