In the How Do I forum there is a thread on how to move servers
How to Move Servers and/or Change Directories
I would suspect you moved servers did not update the server paths saw missing photos and went to admin and ran the scan database tool to rebuild thumbs and since the photos can not be found as the paths are wrong the database entries where deleted.
The only way to restore things is to in admin global options and storage options correct the server paths and restore a mysql table backup of your photopost photos table.
There is