How can i find the total depreciation i used on my rental property before 2000 if i cannot find my tax forms

[KarenL2]

You may be able to calculate it if you know the value you put and the date you started renting it.  Rental property is depreciated over 27.5 years using Straight Line depreciation.  That means, for a full year of 100% rental use, you would take the depreciable value of the property and divide it by 27.5. 

If you can find even one of your tax returns, you can look at the year's depreciation on Schedule E and do the reverse to find the depreciable value. (take the year's depreciation amount X 27.5)

Otherwise you can get transcripts of prior year tax returns from the IRS. Here is the link for the various IRS Transcript Types.  Also, here is the link to IRS Form 4506-T.