I can't create offline games and 1 of my characters was completely deleted!

Hey there JohnGalt,

The inability to join or create offline games is usually due to a damaged file. The missing character is also telling of a problem. Offline characters are saved locally, meaning on your specific system. There is no backup so if it is damaged, there would be no way to recover whatever is found to be corrupted.

Fixing the ability to join games is usually done by renaming or deleting the file for the shared stash.

“C:\Users(your user name)\Saved Games\Diablo II Resurrected\SharedStashSoftCoreV2.d2i"

If deleting shared stash file doesn’t resolve the issue then the issue is most likely with character save file. As mentioned, there is no know way to fix corrupt save files, so the only solution in that case is to delete them and start over. Character save files are named after the characters. There are several files. I’ll an example character named “Barb”. They woul have the following save files:
Barb.ctl
Barb.d2s
Barb.key
Barb.map
Barb.map0

While that isn’t helpful to get the character back, it should let you at least get back to playing a new one. As a side note, it can be a good idea to make regular or periodic backups of the character saves when playing offline as it can help minimize losses in case of a game or system crash causing corruption to those files.