Title text: If that doesn't fix it, git.txt contains the phone number of a friend of mine who understands git. Just wait through a few minutes of 'It's really pretty simple, just think of branches as...' and eventually you'll learn the commands that will fix everything.
Transcript
[Cueball points to a computer on a desk while Ponytail and Hairy are standing further away behind an office chair.]
Cueball: This is git. It tracks collaborative work on projects through a beautiful distributed graph theory tree model.
Ponytail: Cool. How do we use it?
Cueball: No idea. Just memorize these shell commands and type them to sync up. If you get errors, save your work elsewhere, delete the project, and download a fresh copy.
I've been using git for 10+ years and still sometimes do this. I know I could fix it, I also pretty much know what to do to fix it. However nuking the thing from orbit and restarting takes like 30 secs, so it's never worth fixing.