[Abd_von_Mumit]

1. Did you upgrade your game with any mods?

2. Did you edit any save files?

3. Do you use SH3 Commander?

4. Did you come back to older save files using the game's interface (like loading previous one after being killed)?

Before you answer, you could try this:
1. Copy your save files to another, safe location.
2. Start a ne career, go to patrol, save it and quit.
3. It's possible that your previous career is now accessible again.