Major issue. Missing user after complete reinstall of OSX

Hey everyone.

This problem started this morning when there was a problem with my internal HD for Macbook Pro.

I couldn't start up the drive due to some kind of corruption that I believe turned out to be a software issue. I connected up my 1TB external harddrive and installed OSX Mavericks on it. Once everything was finalised, I installed DiskWarrior and repaired my internal HD. There was an error that forced an abort, but now my internal HD was responding and I verified/repaired it through disk utility. I then restarted my macbook through the recovery disk (as it had been before, when my internal drive wasn't working) and selected my internal HD for an install of OSX Mavericks. I installed it to my internal HD and everything seemed like it was going fine. Upon booting, I am greeted with a grey screen with no profile picture or anything. There are only the 'Username' and 'Password' boxes, but no account name above or option to select an account. The account is labelled as 'Other...' (or at least it appears that way as there are no alternatives), and as far as I can tell wont respond to my password or username.

Here's the kicker. I turn the Mac off, and boot up using my external HD with hopes to operate for the time-being out of that (since it worked earlier). I am then greeted with the same grey screen with the same empty account.

It seems that for some reason I am locked out of both drives. I was wondering if there are any solutions to this problem or if anyone ever has encountered the same thing. This may stem from the internal HD issues I had earlier, but that doesn't seem to explain why now my external HD displays the same screen.

All in all, I am dealing with a complete loss of all accounts on my Macbook Pro.

Any help would be massively appreciated, and I apologise for the complex nature of the problem.

Cheers.