I cannot log into the admin user account on Vista.. How can I find the account and reset the pword ?

I have no disk, and all the answers I have gotten have been from people selling a service.. Please, I need help from a person who is not selling a product. I tried to set up two user accounts so i can communicate with a friend who is going to Iraq for six months.. Now I cannot even access the computer because I changed the admin account name and pword and it seems the pword did not take. The old nor the new pword now work.. Stacy had initially set it up under and admin user account.. I gave her account to Patricia and set her up as a regular user then set mine up with my name a admin. complete with pword.. Then i decided to change it to a regular user account and it will now take the pword to enable me to change the account.. I cannot even acces mail or change anything on the computer at this point.. Please help..!!! Terry