All the projects in Trados Studio are randomly removed from the Projects list from time to time. To retrieve them, you re-open the projects one-by-one from their location on the PC. However, the issue is recurrent.

1. Make sure you run Studio as administrator (search Trados Studio in the Windows bar > Run as Administrator on the right side).
2. Change the location of the projects.xml file in SDL Trados Studio.
3. Make sure the project.xml file from C:\Users\username\Documents\Studio 2022\Projects is not Read-only.