Hi @Sewlizette,
Thanks for the note. Welcome to the forum. Yes, I have heard of a few cases where a project was not saved on exit. The project is supposed to save on exit. I do not believe that there is a way to recover your project.
Since cloud sync was removed, projects are not automatically saved to the cloud, so there is always the possibility of losing a project if you crash on closing. It sounds like something similar happened to you. If all your projects got deleted, then something is very wrong. Are you on a enterprise or EDU license? If so, cloud sync was recently removed there, so that could be the reason.
If you maintain your computer and Rush, you can prevent this from happening too frequently. I recommend deleting media cache and resetting preferences periodically if you are on a desktop computer. Let me know if you need help with that. I recommend completely deleting the app between projects if you are on mobile. If you have larger, more complicated projects other than a quick video, I recommend Premiere Pro where more safeguards are in place for mission critical work.
Sorry again for this issue.
Thanks,
Kevin