Hi Shubham,
Greetings!

1. First of all, you have to create a custom field in Lead.
Data Type - Date
Field Label - statusChangeDate
Field Name - statusChangeDate
Default Value - TODAY()

2. Create a Process builder,
Process Name - Lead Status Change
API Name - Lead_Status_Change
The process starts when - A record changes
Click on save.

3. Creating Process builder
    a. Add Object
    -> Object - Lead
    -> Start the process - when a record is created or edited
    -> Save

    b.Add Criteria
    -> Criteria Name - IsStatusChanged
    -> Criteria for Executing Actions - Conditions are met
    -> Set Conditions
        Field - Status
        Operator - Is changed
        Type - Boolean
        Value - True
        Conditions - All of the conditions are met (AND)
        Save
    -> MMEDIATE ACTIONS -> Add Action
        Action Type - Update Records
    Action Name - updateStatusChangeDate
    Record Type - Select the Lead record that started your process
    Criteria for Updating Records - No criteria—just update the records!
    -> Set new field values for the records you update
        Field - statusChangeDate
        Type - Formula
        Value - TODAY() 
    Save

4. Activate the process builder by click on Activate.

5. Create a Apex Batchable and Schedulable class that runs daily sends mail to the owner.

public class LeadOwnerAlert implements Database.Batchable<sObject>,Schedulable {
    public Database.QueryLocator start(Database.BatchableContext BC){
        Date checkDate1 = Date.today()-2;
        Date checkDate2 = Date.today()-5;
        return Database.getQueryLocator([SELECT Name, Status, Owner.Email, statusChangeDate__c FROM Lead WHERE (Status = 'New' OR Status = 'Working') AND (statusChangeDate__c = :checkDate1 OR statusChangeDate__c = :checkDate2)]);
    }
    public void execute(Database.BatchableContext BC, List<Lead> leadList){
        Messaging.SingleEmailMessage[] emailList = new List<Messaging.SingleEmailMessage>();
        Date checkDate1 = Date.today()-2;
        Date checkDate2 = Date.today()-5;
        for(Lead ldObj : leadList){
            if((ldObj.Status == 'New' && ldObj.statusChangeDate__c == checkDate1) || (ldObj.Status == 'Working' && ldObj.statusChangeDate__c == checkDate2)) {
                Messaging.SingleEmailMessage email = new Messaging.SingleEmailMessage();
                email.setSubject('Lead status not changed');
                String daysDifference;
                if(ldObj.statusChangeDate__c == checkDate1) {
                    daysDifference = '2';
                }
                else {
                    daysDifference = '5';
                }
                email.setHtmlBody('Your lead name is '+ldObj.Name+' and status is '+ldObj.Status+' which is not changed from '+daysDifference+' Days.');
                List<String> emailTo = new List<String>();
                emailto.add(ldObj.Owner.Email);
                email.setToAddresses(emailTo);
                emailList.add(email);
            }
        }
        if(!emailList.isEmpty()) {
            Messaging.sendEmail(emailList, false);
        }
    }
    public void finish(Database.BatchableContext BC){
    }
    public void execute(SchedulableContext SC) {
        Database.executeBatch(new LeadOwnerAlert());
    }
}

6. Schedule this batch using Cron expression.
example for a daily morning at 8.

System.schedule('Lead Status Not Changed','0 0 8 1/1 * ? *', new LeadOwnerAlert());

If this helped you please mark it as the best answer.
Thank you!
Regards 
Suraj Tripathi.