As 10 fixed assets

Ascertain the Carrying amount of the asset form the previous balance sheet (even though the records are lost, the balance sheet filed with RoC would be available with payment of nomial fees). On the Carrying amount of the Asset apply the Depreciation at the rate applicable to asset and arrive at the Book Value of the Asset sold, Determine the profit or loss on sale of such asset.

You would have shared the FA schedule with auditors. You can get the details from them on request.