If you used the Desktop CD/Download installed program then the only copies are on your computer and not kept online at Turbo Tax. So you should have both the pdf files and .tax files for each year. They should be in your Documents then in a Turbo Tax folder or search your computer for them. And check your backups for them.
If you can't find your return, request a free transcript of your federal return from the IRS.
http://www.irs.gov/Individuals/Get-Transcript
Or order an exact copy of your tax return (including all attachments) from the IRS. There is a $50 fee per tax return. See
http://www.irs.gov/taxtopics/tc156.html
