If you find yourself in the uncommon situation where you have forgotten your user password and can not access your Windows account, here's a short trick which will give you access to command prompt in order to reset your password and eventually gain access to your Windows account.
Prerequisites: this trick works only if you have a local Windows account, in case of Windows 8/8.1 not connected to your Hotmail or Windows Live account. You also need a Windows installation disk or USB.
Step 1: Boot your computer from DVD or USB. This will start loading files for Windows installation.
Do not press "Install Now", but go for "Repair your computer".
Step 3: On the following screen, press "Advanced Options"
Step 4: On the "Advanced Options" screen, press "Command Prompt"
This will start a console window. Type the following command:
copy c:\windows\system32\utilman.exe c:\
Press Enter key. You should get a verification message of 1 file copied.
copy c:\windows\systems32\cmd.exe c:\windows\system32\utilman.exe
Press Enter key. You should get a message for file overwrite. Enter Y or Yes and press Enter key. You should get a verification message of 1 file copied.
Step 5: Remove your Windows installation disk or USB and reboot your computer.
Step 6: On the Login screen, press the "Ease of Access - Accessibility Options" button.
If you followed the instructions correctly on steps 1 to 5, this will eventually give you access to Command Prompt (!!!) instead of Accessibility Options and enable you to run commands to reset your user password on this Windows installation.
Step 7: Type the command net user and press Enter key. You should get a list of user accounts and usernames on your Windows installation and this list should contain the user account you can not access. Make note of the username of this user account.
Step 8: Now, it is time to reset your password. Type the following command:
net user "username" newpassword
Replace username with the username you noted from the usernames' list. You can ommit "" if username consists of only one word. Replace newpassword with a password of your choice.
Step 9: Restart your computer and login into your account with the new password that you have set.
Step 10: if you want to recover the "Accessibility Options" button functionality (...well, if necessary, I wouldn't mind having access to command prompt instead of Accessibility Options...), open a command prompt window and type the following command:
copy c:\utilman.exe c:\windows\system32\utilman.exe
Press Enter key and type Y or Yes on the file overwrite message. You should get a verification message of 1 file copied.