You may have worked more then one copy last year. This can happen if you saved a copy before completing the return. On File Explorer, check last years files for more than one copy (not pdf copies). Note the dates last modified (saved). Re-open TurboTax. At the page where it says to select last years return, don't choose the one displayed, but choose browse and select the latest one. If tht one doesn't work, try the other one.
