I think you mean “corrupt repository” - a project history can get corrupted by different problems on a computer.
When the project history is corrupted, you can still open and edit the project, but will not be able to add more history to the project (like with “Mark point in project history”) or do a send/receive.
I normally recommend these steps to recover a project:
- Backup your project
- Restore the backup to a new project name
- Delete your local copy of the project
- Retrieve the project using send/receive
- Use Tools/Compare Texts to find changes between the restored project and the project created in step 2.
You can find more detail on these steps on this page: https://lingtran.net/Temporary+new+project
John+Wickberg
Paratext support