Used Diskwarrior and now all users are gone

Hi, my girlfriend was using her Macbook Pro as usually when the Safari browser froze. She used the power buttom to turn it off and when she turned it back on her discs were gone. Now it was only possible to log in on the recovery-10.9.3.

So I used the disk utility, which showed that her partitions under a new names (Toshiba 750 Gb something). I ran the verify Disk and repair disk tools, which told me that there was a "Invalid B-tree Node size error" or something. There's is some importatnt files on the her hard disk (and of cause no backup) so I didn't dare to erase it completely. So I read about it and figured that I needed to run the Diskwarrior software.

I went to the local apple store where a very helpful guy helped me. Diskwarrior couldn't find the right disk, but it found a disk called "customer" which we ran the software on. After this the disk changed name to "untitled" and the disk utility no longer found any problems, so I went home because I though I only had to setup the system again. I reinstalled the OS, but now there is only a user called "Other..." that needs a Name and a Password (neither of which we can figure out).

I cant boot the su (CMD -S) directly from startup. I can boot from the Recovery partition, but I can't run the "sudo" command from the terminal window found in there.

Anybody have an idea on how to get out of this little pickel without erasing everythin?

Nicki