@MAXLDThx alot mate!

I could solve the problem in a similar way yesterday evening. Just one difference: In my case I did not have the option of loading another career file.

Solution: Follow the steps mentioned in the accepted solution. When you left the new career and are back on the home screen, minimize the game, rename the career file you want to load (so it's the one with the latest date) and delete all other career files. This is happening in the concrete settings directory of course, not ingame!

I then entered the career again from the home screen (it showed the next game preview from the new career still) and it loaded the old career game that I actually wanted.

Probably this happens because it's the only available file in settings then.