Windows update destroyed my logfile!

[Shad]

So, am I screwed, or is that stuff hiding in the file somewhere?

You're screwed.

And if not, how do I satisfy the PG-Über requirement? Can I just restart the log and submit the Turn 3-5 stuff for full credit? 

This is fine. Just add a comment to the start of your log so the mentor who reviews it understands what's happening in case they don't see this thread.