On start up hold down F8. You should get a menu. "Windows Advanced Options Menu". On that menu, there should be an option to boot in safe mode. You may get a screen saying "Please select the operating system to start:" first. If so, then press F8 to get to the advanced options menu. After making the selection at the Advanced options menu, you should be at that screen and "Safe Mode" in blue should be at the bottom. Hit enter and a series of lines beginning with multi(0)disk(0) should go across the screen. You should then see a black screen with "Safe mode" in the corners. Eventally the welcome screen will come up. There may be several accounts available, and some may not be immediately visible. If you can see the Administrator account click on it or highlight it and press enter. If you cannot see the Administrator account, pressing down arrow should bring it into view.
You will see a dialog box that will tell you about safe mode. Click "Yes" here.
Go to the "Start" menu and click on "control panel". Look for and select the "User Accounts" icon. You will see a window with the words "Pick a task". The first choice under that is "Change an account". Click on "Change an account". One of the accounts there should be the one you can't get into. Click on that account and you will be given another set of choices. One of them is "Remove the password". Click on "Remove the password". You will see a window with "Are you sure you want to remove account's password". There will be a button that says "Remove Password". Click on that and after rebooting you should be able to access that account again.

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