I, would like to know about 2000 tax deductions allowed by the IRS on what is consider reasonable?

I, will need to complete schedule 1040 A, for the IRS. The documents that I, have are either lost, misplace or not available at this time to verify my current deduction for the year 2000. The IRs want me to submitt this document in order to determine if I, owe back taxes for this year.