Credit on excise return

Dear Sir,

Kindly help me on below mentioned question:

We received some sales return of excisable goods.

Can we take credit for the same in RG 23A Part II?

Which documents are required for the same process?

Our vendor is not registered under excise?

Is there any time limit for taking the excise credit?

After the sales return we have to file revise return or not? and what is the process for the same?

Are there different conditions in sales returns for the excise credit. ( I mean reason of sales return matter while taking credit of excise)?

Kindly help me on all above question.

Thank you very much in advance for your kind co-operation.

Thanks

Ajay