I don't have a Form 16.

You can still file a tax return without a Form 16. 

Are you a salaried employee and do you have all the payslips for the year? 

* Add up all the after-tax amount for the 12 months. That is your income from salaries. 
* You will also find the tax getting deducted each month. Add it up. That is your TDS. 

I don't have payslips. What other options do I have? 

Ok, breathe! You're going to need:
* Bank statements for the account where your salary gets credited. 
* Form 26AS to find out how much taxes were deducted.

This will give your salary and TDS.

Do you have to claim HRA? 

* Claiming HRA becomes tricky if you don't have payslips. 
* Look for your offer letter and use an HRA Calculator to find out what amount of the HRA counts as an allowance. 

Deduct the HRA exemption from the salary and put the final figure.

Do you have any investments that you have not declared to your employer?

* Claim the investment directly in the tax return under Deductions on ClearTax: https://cleartax.in/paytax/y2016/0/Deductions

Submit a request if you need any further help.