This may help if you need to restore your numbers. I had to redo my files when I switched from a garmin power meter (the estimated ‘z’ power) to a real power meter because all my stats were 35 watts too high. In your zwift, you can delete a specific activity or file (or all of them) You can simply rename the file for storage or delete it and Zwift will continue as before. You will still have the same accumulated mileage, points and everything. but all your best rides will be reset to zero (if you remove all files) or restore to the same previous numbers (before your friend rode and lifted your ftp/best 20 minute effort from 115 watts to 200, for example.) You simply select the date of the activity you want to delete.
A quick explanation is here: https://www.youtube.com/watch?v=Z__7_6u5PRw