Forget to mention my aadhar no

@ raja P M I verified with bank account but I failed to mention it in my ITR form . Its not mandatory to mention aadhaar ?

I tried to link but it ended up with name mismatch error..

One side question my friend usually play games in classic rummy he deposited 100000 but he earned 60000. SO he is in loss of 40k now but classic rummy charged 30% in TDS for his earning of that 60000. He is a salried person and his salary is below the base exemption limit .. Now if he files nill return he can claim that tax deducted amount ?

And thanks for ALL the replies

Yes. But filing of the return within due date along, with the actual amounts are must for claiming, 

Thanks for the reply. He can file ITR income from other resources as zero ?