Glad you got it working again!
Everything uses 2 different, deeply hidden, Windows files for detecting what files are on you system.
One is the "address book" of all files and the other is a logfile of all changes to the filesystem (new/changed/deleted files).
Sometimes - very rarely - Everything misses some file changes from the logfile.
A 'Force Reboot' re-reads all files from the 'address book'
Other possible explanation: your database was corrupted.
Make sure you are on a recent Everything version ( 1.4.1.935 or higher ) to minimize those misses.
If this happens again, please report back. There are fixes for that too
