'k now get this
ubuntu 16.04 live disc has a repair/reintall option, it'll replace the OS and reset all OS settings but try to keep installed apps and definitely keep user data
LIKE A FOOL I TRIED THIS HAHAHAHAHAHAHAHAHAHAHA FUCK ME
FIRST thing it does: mount the old OS drive and delete all the old OS files.
SECOND thing it does: unmounts old OS drive
THIRD thing it does: tries to remount old root (which it mounted before, I note) as ext2 file system. BUT if it's NOT ext2...
THE WHOLE THING PUKES AND DIES AFTER COMPLETELY DESTROYING WHATEVER REMNANTS OF AN OS YOU HAD ON THE PARTITION.
HEY IF YOU'RE GONNA DIE IF NOT EXT2 YOU MIGHT CONSIDER CHECKING FOR EXT2 BEFORE DELETING THE ENTIRE OS.