[BO] Need help on corrupted multiplayer account Steam

This shit happends every time i level up. Im having this issue for about 3 years now and every solution i could find on the web doesnt work. I tried to play through it but it always resets me back. I was prestige 4 lvl 42 and i have 5 classes with weapons a level 19 couldnt have in his inventory. I also cannot change the loadouts because it will download game files and reset me back. Please if you have a possible solution please lmk or if you have a similair experience.