Hello Henry,
I'm sorry to hear you're having trouble with a Team Project. Based on your description, I suspect there are one or two assets in the Team Project that have become corrupted. It should be possible to recover everything to the state it was in when you last shared, via the Media Browser:
1. Create a new Team Project
2. In the Media Browser, Navigate to the Team Projects view (under "Creative Cloud")
3. Navigate to the Team Project that you are unable to open.
4. Click on the button in the upper-right corner of the Media Browser (the tooltip reads "Toggle Team Project History Slider"). This will enable a slider on the right side of the view.
5. Move the slider to the previous version of the Team Project.
6. Select all, and either drag them into your new Team Project or right-click and choose "Import" to import them.
With your permission, I'd like to take a look at your Team Project to look for clues about what went wrong. Hopefully the issue is due to a bug that we've already fixed for an upcoming release, but I would like to be sure. If that's OK, please PM me.
Sincerely,
-Peter Lee
Adobe Team Projects Engineering