Nilesh,
It is not clear from your Post the followings:
1. Are you still working or left the job?
2. Have you given any application to your co. for payment of Gratuity.?
3. What was your date of joining & date of leaving.
4. What was your nature of work.
5. Have you worked 240 working days in every calendar year (Not paid days).
Please write to your employer with full details of your designation, date of joining, date of leaving and inform them that you are entitle for Gratuity payment as per the act and hence release the payment.
You may also attach your bank statement or photocopy of passbook duly attested by you as an evidence that you were getting salary/wage from them from your joining time.
If you feel that your employer will not respond to your request, you may mark copy of that letter to the Labour Officer of your co's. Jurisdiction alongwith photocopies of your bank statement and or whatever proofs you are having such as Identity card, attendance card, Salary slip and PF A/c. statement etc.
If whatever you stated in your Post is correct, then you should get Gratuity payment by producing the above documents / evidences.
Suresh