Am I able to Amend or lookup a 2010 return?

TurboTax only retains online tax returns for the past 7 years, the same retention period as the IRS.  The 2020 tax return is no longer available.

No.   TurboTax saves returns for seven years.....just like the IRS.

No.  The Internal Revenue Service limits the amount of time you have to file a 1040-X to the later of three years from the date you file the original tax return, or two years from the time you pay the tax for that year. 

Taxpayers can request a copy of a tax return by completing and mailing Form 4506 to the IRS address listed on the form. There's a $43 fee for each copy and these are available for the current tax year and up to seven years prior.