For what suit can I file in civil court

Your elder brother receives the amount from the Bank as a Trustee only. As the nominee, he can only receive the deposit amount from the bank, and he cannot appropriate the entire amount for himself. It is his bounden duty to share the amount of deposit so received from the bank, among the eligible legal heirs.  Nomination for a bank deposit is not a Will. It only facilitates the amount to be received by a person named as Nominee by the Depositor so that claim settlement becomes easy in the event of death of the Depositor.

Therefore, you may inform your brother of the above facts through family elders and have an amicable settlement. If everything fails, of course, legal action is there at which time you need to go to a local reliable Lawyer with full facts and get guidance.

Father assets can be divided equally among legal heirs if WILL is not existed. 

What is the present status of the deposit? As the nominee, has your brother receive the amount?

Are you the only legal heir other than your brother?

File a petition for succession of the estate of deceased before Civil Court of jurisdiction through a local prudent lawyer.