hello!
I would recommend you two steps,
1. Check your games files, on steam.
On Steam, go to Euro Truck Simulator 2, then go to properties, and check your files.
2. If that’s not working, try to uninstall your launcher, and files and reinstall it properly, maybe it will work.
Maybe you can also check if your drivers are up to date, this can also be the reason of this.
hope it helps,
have a nice day