Unfortunately there is no easy fix for a situation where you have lost receipts for expenses which you claimed a tax deduction for.
It is a taxpayer's responsibility to keep all tax records which will prove or substantiate income and expenses which were claimed on your return. Without those records, in the event of an audit, the auditor is not required to allow you to keep deductions which you claimed. The very best you can do in a situation like this is first, try to replace any receipts that you can. If that is not possible, you can try to get affidavits from people or companies who you incurred an expense with to attest to the fact that you spent a certain amount of money with them and the reason for the expenditure. The third thing you should do is try to create a detailed log of the expenses you claimed, showing as much detail as you can about the date of the expense, what it covered and who it was paid to. You should also try to tie in your various expenses with bank records that show amounts withdrawn for various reasons.
There is no guarantee that the auditor will allow the expenses claimed without having actual receipts, but the more you can put together to show the auditor that you are making a true effort at cooperating with the audit, the better off you will be.
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Thank you virgil