Use the NT Password reset tool to find the username and reset it's password.
Here is a guide on how to use the tool: Quick Guide - How to Use Offline NT Password & Registry Editor
And here is the page where you can download the tool:
To create the tool you will need to do this:
They have a CD version as well as a USB Stick version. I recommend you do the USB version. Download the zip file, extract the contents to a blank usb stick, then run "syslinux.exe" from the USB stick and follow instructions.
Reboot your computer and see if it loads the tool automatically, if not you will need to lookup how to get to the boot menu for your computer.
Edit: didn't see that it was already resolved. oh well.