Characters keep disappearing

Hello,
I couldnt find a thread about this so im just going to open up this one.
I recently have a problem that my characters keep disappearing. When i create a new character and play the game everything is fine. When i save it and exit the game and reopen it i can still find my character but once i shut down my pc and a day later after rebooting my character is missing. Now i recently created a new one because i was hoping that it wont happen again and today i wanted to play again and now the new character is gone and the old one that disappeared for some reason is playable again. I really dont know what is going on. I hope you guys can help because im really bummed that i cant play the game like this.
Thank you !