2 ways -
This procedure only works if you can enter safe mode thru the hidden Admin Account
1-Boot to Safe Mode by tapping the F8 key while booting
2-Choose safe mode, Press Enter
3-Select operating system, Press Enter
4-Click Administrator Account
5-Windows is running in Safe Mode, Click YES
6-At the Safe Mode Desktop, click, Start, Control Panel
7-Double click User Accounts, Here you can delete accounts, delete/change passwords ETC.
8-When done Close all Windows
9-Restart Computer To return to Normal Start.
Using Start - Run to change Password.
Click on Start-Run, type: CONTROL userpasswords2, then click on OK. When the "User Accounts" window loads, click once on the username you wish to change the password for, then click on the "Reset Password" button. At the next window, type the new password twice, then click on OK and restart the computer. You'll need to use the new password when you access the login to the normal user again.
Restart Computer to return to Normal Start.