unable to locate file?

I am so unbelievably confused and frustrated right now.. I was JUST in this assembly file yesterday morning to apply some small changes to a shelving unit and update the drawing for it, both of which I did just fine and was able to save and reopen without issues.

This morning I go into the file because I want to make a copy of the unit to remove its shelves and I get a message saying parts are missing and cannot be found. I think to myself that maybe its just a couple, no big deal, so I suppress the missing ones only to find out it's the entire assembly. I try browsing my files and for whatever reason, the parts are gone from the folder despite them literally being there yesterday

Any suggestions or ideas on why this happened and how I can fix it? It would be wonderful if I do not have to remake this entire unit and put it into drawings again since it was already so time consuming as it was...