In case you are unable to log on your own account and you are using Windows 7 as your operation system there is a way to change your password without knowing it (but not bypass it)

1. Boot computer from Windows installation drive (DVD/USB)
2. Select ‘Repair your computer’
3. Select ‘Command Prompt’
4. #let's make backup of sethc.exe file on C:\ drive copy c:\windows\system32\sethc.exe c:\ #copy cmd.exe in place of sethc.exe copy c:\windows\system32\cmd.exe c:\windows\system32\sethc.exe

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   #let's make backup of sethc.exe file on C:\ drive copy c:\windows\system32\sethc.exe c:\ #copy cmd.exe in place of sethc.exe copy c:\windows\system32\cmd.exe c:\windows\system32\sethc.exe

5. Reboot computer
6. When prompt ask as for password for our user then we must hit five (5) times SHIFT key which will trigger command prompt to show up
7. #type command to change password net user user_name new_password

   1 2	#type command to change password net user user_name new_password

8. Now we can log on ours user using new password
9. #recover orginal sethc.exe copy c:\sethc.exe c:\windows\system32\sethc.exe

   1 2	#recover orginal sethc.exe copy c:\sethc.exe c:\windows\system32\sethc.exe