My game progress has disappeared.

Hello, my FaceBook account was deleted for unexplained reasons a year ago. My game was linked to an erased FaceBook account. At the beginning I didn't remember that the game was connected to the old account, because I could play normally, but a few days ago I was logged out and I cannot log in to my previous account. I have been playing the game for over 5 years and I have reached the level of 2500-3500. This account was very important to me because I played the game in the evenings and loved it. I am asking for help, I don't know what to do.