Second USB?
The fast route first
FILES ARE VISIBLE
Your files are readable, so the fast, safe route comes first. With a second drive, your original never gets touched.
This computer has rekordbox with your library on it? Take the export rescue instead: a fresh export keeps your cues and playlists, a raw file copy does not.
Do you have another USB you can use right now?
You follow these steps at your own risk. Full disclaimer.