Cannot Log In To Mavericks User ("No" Symbol)

I'm working on a colleagues computer (early 2009 13" aluminum Macbook Pro). He upgraded to Mavericks a few months ago and the computer has been running fine. Yesterday I upgraded Mavericks to 10.9.4 with no issues, so that's what it is currently running.

For work purposes, I had to encrypt the computer using FileVault2. I started the encryption process, and it told me to restart the computer to complete the process. I restarted the computer, and it came up with the normal log in screen (his user name or Guest). I put in his user name and password and then all I got was a spinning gear with the Apple symbol. After a few minutes the Apple symbol changed to the universal "no symbol" (circle with a diagonal line through it).

Things I've tried that haven't worked

• Going in to recovery mode (command + R on restart) to enter disk utility and check the drive. The partition is greyed out and I can't verify or repair disk permissions, but I did verify the disk itself and it had no problems.
• PRAM reset didn't do anything
• SMC reset didn't do anything
• Logging into the Guest account just hard restarts the computer and then brings up Safari, with no access to anything else.

Any advice on what to do would be great! He does have a backup thankfully but I'm not ready to restore from backup yet considering he hasn't backed up in a few weeks. I'm holding out hope for the data on the computer.