Hi it seems you have a duplicate question open that another expert has already provided an answer for here
Please continue working on it there
Do you know what version of OSX is on the computer 10.1 10.2 ...10.6?
Hold apple + s down after you hear the chime.
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
After rebooting you should have a brand new admin account. When you login as the new admin you can then go into accounts and change the password XXXXX the account you cannot get into this will give you access to the account
let me know if you have any questions
how do I log in?? what do I print in boxes?
do you not see the user names that you can click on ?
If not try admin for user and leave password XXXXX
what information is the sign in box asking for?
if its username and password XXXXX
Admin with a blank password