The limitation period for any claim is 3 years from the date of last cause of action.
You may approach a competent and experienced service lawyer with your letter of appointment, certified standing orders of the company and any other document that may be useful to make out a defense to protect you. You may look into the SE act applicable to your state. It is felt that you were in training or probation period while you left.
Employee should not separate in the manner you did. You should have sought advice from elders in the family, competent and experienced well wishers, trained legal mind at that time. Please get into the habit of discussing matters in time. Good piece of advice in time shall protect from loss later.
In today's business environment each payout and each payment that can be accrued is looked into and employers chase the employee. Employer do engage lawyer/law firms for recovery and law firm may get portion/percentage of the amount it succeeds in recovering so employer doesn’t have to pay beforehand and hence there is no cost in advance.