it is gift from father to son 

there is no agreement to pay interest nor is there anything in writing that it is a loan 

there is no presumption of any gift just because the father's cheque was deposited in your account

your father can ask for a refund 

however he cannot claim interest on it since you were not informed about the deposit in the first place

Friend of father has withdrawn a certain amount from the you account through cheque. You can certainly recover the amount from him with interest and expenses as there is proof of withdrawal from bank through cheque. Issue him a lawyer's notice  seeking payment  with interest within fifteen days after that file a money suit for recovery of amount with interest and expenses. You will get your money back.  

- Since your father has deposited the said cheque in your account without entering into an contact even orally , then it cannot be considered as gift from father to son.

-Further, he can ask for the refund of the said amount without any interest . 

Keep the money 

there is no agreement executed that funds have been given as loan and has to be returned 

- Since there is not agreement with you that during a particular fixed time you have to refund the amount , then you can keep that amount with you . 

He can't ask it as a matter it right he need to prove that it was a loan given to you

If your father has given you some money that cannot be considered as a loan unless sttaed otherwise.

Therefore you must ask and find out the reason for depositing the money.

A father can give money to his son  and i don't think there is any problem unless of course relationship is strained/not good between you two.

Dear Sir/ Ma'am,

Since you were not aware of it and neither do you have any contract regarding the same, this cannot be considered as a gift. Try contacting your father and clear this out with him, since this is an amount that he can claim later.

Thank You

Your concept is not understood.

If your father has deposited some money to your account without your knowledge then you can deem it to be a gift from your father if in case your father is not demanding it back.

In what way does your father's friend would be demanding money from you if he has not given any money to you but had given it only to your father.

You do not have to entertain your father's friend's demand for return of money because he had not paid any amount till date to your account with or without your knowledge/consent.

If your father is demanding the return of money given to you then you may first ascertain that why should he give you this money on that day and why is demanding the return of the same, and you may also deny to return the money stating that it was given as gift hence you are not liable to return it. 

since it is your father who had given this money to you that too without even your knowledge about it, you can very well spent the same as your own money.

If at all your father states that it was given as loan, let him prove it.

The next option before you is to ask your father directly about this and know about his intention to transfer this amount whether it was an intended gift or loan  and clarify from him whether it is to be returned or that you can spend it on your own as per your will and wish, this will stop you from unnecessary worries in this regard. 

you can simply return it to your father by transferring the amount to his bank account 

the transaction would close