first try some troubleshooting steps of your own. save the return and reboot. do not reopen TurboTax. when the file was opened before the app creates a backup preceded by a til ~ should be something like ~xxxxxx.tax2020.
make a copy of it. then double click on the copy and see if that works. if so you can rename it to whatever you want when you save it. if this doesn't work
here's the contact web page