I just saw you posted the same at general discussion. anyway, the same I posted there here, in case you see this first:
If your save is broken, there's another way. You can simply restart the chapter. Open the menu, choose "Episode", difficulty and you can start chapter 3.
If you've already escaped from the police, you can start at the mining museum. Otherwise you have restart the entire chapter.
You're send to chapter 4, after you've beaten chapter 3. So don't worry. You only lost progress, but no collectibles or anything.
Don't worry about collectibles, they are all saved and you don't need to collect them a second time.
At least that works for the X360-Version I played. I assume, the same goes for the PC-Version.