form 16  helps you in filling your returns but its not compulsory to  attach with returns You can file your returns even without Form 16. If you know the salary particulars, such as  

 1) amount and date of t.d.s dedcuted,

 2) allowances  under section 10 , 

 3) deductions  under chapter vl a  .

 note : information of  above  will be given in form 16