I finally found .tax2022 file, but turbotax won't let me go back to the page where I can upload it. How do I get back to the beginning?

Is the .tax2022 file on your computer?  You need the 2022 desktop program to open it.  Start the 2022 program and go up to File-Open.

If you have to install the program or reinstall, the first thing to do before you open your tax return is to update the program and install any state programs you had. Then open your file. So you first might need to start a fake return to be able to download the state program (go to FILE - NEW). Enter some basic information, then go to the state tab and download the state program. Then try to open your existing return, go to FILE - OPEN

Oh,  are you trying to transfer 2022 to the Online 2023 return?  If you used the Desktop program last year here’s How to transfer into the Online version. You need to have the prior year .tax2022 file on your computer.  You need to clear and start over to transfer from last year.  

Expand the link if you used the CD/download last year........
https://ttlc.intuit.com/turbotax-support/en-us/help-article/import-export-data-files/transfer-last-year-return-turbotax-online/L279eUvY2_US_en_US?uid=l8w7nlbv