Ohh I've found profile backups.
They are located in: C:\Users\{username}\Documents\Euro Truck Simulator 2\
- Rename the 'profiles' folder to 'profiles.old' (In this folders are the profiles in which your broken profile's located)
- Rename the 'profiles(...).bak' folder which have the change date when you first startet with Truckers MP Launcher to 'profiles' (maybe you have more than one, so just take a look on the change time and choose the older backup)
- Try it out in SP-Mode
- If your game is still crashing, take an older backup
Now you have your working profiles, not up to date but they're working and you don't have to start over again. You just loose everything you've made in Multiplayer
Hope it helps