Ay 11-12 bal. sheet not available-how to file return 12-13 ?

Hello everyone,

i want to file return of my client for ay 12-13.

his return for ay 11-12 was filed online by someone else and that person is not traceable.

my client has only acknowledgement of return for ay 11-12. he do not have balance sheet.

how can i get balance sheet details like op. capital, assets liabilities etc ?

waiting urgently for your reply. thanks in advance.