I think what happened is that the USB froze when you pressed stop, which has left Audacity in limbo.
I assume that Audacity is still open in the same state?
If so, what I would do first is to make a copy of the entire temp folder - this may not do you any good, but at least you will be no worse off if the next step fails.
The next step is to force-quit from Audacity. Open the Task Manager and Exit audacity - don’t exit the program from the Audacity File menu, you need to “kill” it (essentially you are forcing a crash). Then cross-your fingers and restart Audacity. What should happen is that Audacity’s automatic crash recovery should kick in and recover the project, thus allowing you to save it.
To help avoid the problem in the future I’d suggest that it may be worth dropping the sample rate to 44100 or 48000 Hz. For sample rate, more is not necessarily better. Marketing hype often tells lies - sound cards usually perform better (higher quality sound) at 44.1 or 48 kHz than at higher rates, and higher sample rates put a lot more demand on all parts of the system.
Another trick that often works is File > Exit (which is active in your first screenshot). This will probably ask you to save changes and avoids having to force quit. But make a copy of the temp folder first, as Steve says.