How to restore user account from different boot? So I did something dumb and now I'm locked out of my Mavericks partition on my MacBook. The dumb thing I did, specifically, was trying to change the user folder using the Directory Utility app, which should have worked but it didn't for some reason, and now I can't log in. Still have a Yosemite partition on the same computer though.

What I want to know is, is there a way, from outside the Mavericks boot, to change the home folder info? I know this info must be in some config file somewhere, however deeply hidden. Failing that, can I create a guest account, or enable root user, or any of that magic from outside the boot?

Oh, and please don't take this opportunity to lecture me about backup drives. The one I was using failed and I'm a student who can't afford another one right now. Life is hard.
Boot to your Recovery HD or the Yosemite volume. Then open from the menubar Utilities -> Terminal (Recovery HD) or Go To -> Utilities -> Terminal (Yosemite)


Enter cd /Volumes/name_of_your_Mavericks_volume/private/var/db.  
List the content of the folder with ls -laO. A file with the name .AppleSetupDone should be listed amongst other files and folders.
Then enter rm .AppleSetupDone booted to Recovery HD (or sudo rm .AppleSetupDone booted to Yosemite) and then exit. 


After rebooting to your Mavericks volume you will be asked to configure your OS X. Create a new temporary admin user. Log-in with the temporary admin user and repair your main admin user with Directory Utility.