Before doing such a radical restoration attempt, you really should ASK before you make a (possible) simple issue into a Major OMG
A 'additional Filter' might have been in place (if you see a Red Minus near the search bar) or you were viewing a VL tab
Kind of late to troubleshoot.
BTW I have done 100's of updates since 2010. Things have gone south before (I also sometimes run betas).
BUT
My Library has never been destroyed without my help

Usually, clearing a corrupted configuration or Reverting to the prior version makes it good again.