What are you trying to do?  Do you need a copy of your 2009 return?  Even the IRS only keeps the last seven years

I plan to sell a rental house that I have owned since 2003.  I see in the formula for capital gains tax that depreciation is needed for the calculation.  If tax returns are only needed for 7 years, how is that value found?

It should be on your last year's tax return.  Print out your return with all the worksheets.  There might be a depreciation sheet.