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.
If you used the Desktop CD/Download program then the only copy is on your computer and not saved or stored online. So you need to make and keep your own backups.
You have clicked a link to a site outside of the TurboTax Community. By clicking "Continue", you will leave the Community and be taken to that site instead.