Any ideas.
Using Force Quit assumes you are on Mac, more details would preferred, we are no mind readers nor magicians.
First hold down option key while restarting Bridge and choose reset preferences, if still in trouble quit Bridge and go to your user library (by default hidden, use Finder Menu Go with option key)
Search in this user library for the folder Caches/ Adobe/ Bridge CC. Inhere are two items, a plug in and and a folder called cache. Drag both items manual to the trash and restart Bridge (both deleted files will be replaced with fresh new files.
Try again, you will need to cache your folders again once, this takes a bit of time.