Did the IRS ask you to send another one? Or is the website saying Not Found?
How to Access prior year online returns
https://ttlc.intuit.com/community/prior-year-return/help/how-do-i-access-my-prior-year-return/00/270...
If you can't get the side menus to open up to access the prior year..... You need to start entering some basic Personal Info in 2021 for the side menu to open up. Just continue a little ways into 2021.
