Lightroom :: 5 - Lost Connection To Picture Files?

Today I upgraded LR from 5.2 to 5.3 and then began editing pictures. When I tried to delete a picture a message came up to the effect that the file could not be permanently deleted from the disk since it could not be found. It offered the possibility of erasing the file permanently still. I chose that and the picture disappeared  and a small box flashed by which said that the file could not be found. The number of files in the folder didn't change. How do I reconnect to the picture files which are in a stand alone hard drive - And - will the editing I did today be lost of subsequently be connected to the appropriate picture files/