Games do not start (Pc) because of the new hard drive?

Games like Fortnite

Games for Steam are working fine.

Fortnite I come only to the loading screen after that is nothing more

There's always something like DVD drive as a mistake. No idea what they mean.

What do I have to do?

Presumably, the drive letter has moved, so what was before D: E is now:

What you can do: restore the old order (right-click Windows Button> Disk Management> right-click partition> drive letter.) Or reinstall the game.