Hi,

Does anyone have save-files to share?
Cause I can't return to the underground when the bridge has collapsed.

When you run the game on Vista, the save-file is stored under:
program files - gog.com - alone in the dark - indark

The game isn't very long to begin with and most of the early fights can be avoided.
So you can just redo what you did before you made the bridge collapse in less than half an hour.
It's faster than waiting for someone to give you a save file. I have only a file right in front of the final boss.