You can try this:
But, it will create a new account and your old files will still not be accessible.
Creating a new Admin on Mac Os X:
Here's how to reset your OS X password without an OS X CD.
the Working solution for me was to create a new admin
you can create new admin like this by deleting a specific file.
You need to enter terminal and create a new admin account:
2. Hold apple key + s key down after you hear the chime. (command + s on newer Macs)
3. When you get text prompt enter in these terminal commands to create a brand new admin account (hitting return after each line):
mount -uw /
shutdown -h now
4. After rebooting you should have a brand new admin account. When you login as the new admin you can simply delete the old one and your good to go again!