I was pruning old ILL records from the catalog yesterday when I accidentally deleted some video that was actually in our collection. There is no undo button when cataloging, but I knew all was not lost.
When you delete an item in Voyager, a line is added to the log file /m1/voyager/xxxumb/rpt/delete.item. You can find the format for this file in the Technical Manual, Chapter 20 - Item Delete Standard Interface File. It contains all the data necessary to recreate the record and attach to the proper MFHD.