Been there (yesterday in fact) 
All right, I’ll try to find an older version.
I also tried sync after flashing a flash drive through disk image writer and it still didn’t work for me - the flash wouldn’t show up on boot.
Edit: Tried to get an older version, flashed it using disk image writer, entered ‘sync’, and it didn’t get detected. I think for now I’ll install Xubuntu. Guess this is a lesson for me to keep backups.
Hmm. I wonder why this is happening in the first place.
Yeah, even for a static release distro, rolling stable, immutable one, backups are always a good idea. Computers and other electronics can have issues at any time.