Which operating system ?
Restart your computer repeatedly tapping the f8 key to enter safe mode while the screen is black once in safe mode where the only things working will be your keyboard and mouse allowing you to attempt to repair your computer
Windows Advanced Options Menu
Please select an option:
Safe Mode with Networking
Safe Mode with Command Prompt
Enable Boot Logging
Enable VGA mode
Last Known Good Configuration (your most recent settings that worked)
Directory Services Restore Mode (Windows domain controllers only)
Start Windows Normally
Return to OS Choices Menu
Use the up and down arrow keys to move the highlight to your choice
select safe mode with command prompt
Click start run type cmd press Enter
black screen should open DOS mode
this will vary depending on your operating system
type in net user username
For eg. If you want to change administrator password , type net user Administrator
It will prompt you to enter the new password.
Enter the new password and the password is changed
if this fails you will need to
Select safe mode with networking to download
you could download all of these or just one save them to a usb drive for later use if one fails to remove the password
Windows Password Recovery Basic
A CMOS BIOS password recovery tool
Editors note: This tool should only be used by experienced computer users.
Please see the enclosed read me if you would like to run it from Windows.
Failure to follow instructions (from Windows) will cause your anti-virus to flag this as a virus.
Dr.Freeware System Utilities which includes data recovery software, data backup, password