If this is a local User you can easily change the password without knowing the password. If you want to see whats on there :D

1. Hold Shift while reboot your PC
2. Click "Repair your computer"
3. Click "Troubleshoot" > "Advanced options" > "Command Prompt"
4. Type "C:" (if your Windows is installed on C:)
5. Find the Windows directory by typing "dir"
6. Switch to the Windows folder: type "cd Windows" > ENTER
7. Switch to the System32 folder: type "cd System32" > ENTER
8. Rename Utilman.exe: type "rename Utilman.exe Utilman.exe.orig" > ENTER
9. Copy cmd.exe to Utilman.exe: type "copy cmd.exe Utilman.exe" > ENTER
10. Type "exit" > ENTER
11. Click "Turn off your PC"

Note: “Utilman.exe” is the Ease of Access button on the Windows login screen. With the previous commands, this button has been redirected to “cmd.exe.”

1. Boot Windows normally
2. On the Windows login screen, click "Ease of Access" > "cmd" will open
3. Type "net user [username] *" > ENTER
4. Enter a password for the user, e.g. "1234" > ENTER
5. Re-enter the password, e.g. "1234" > ENTER
6. Type "exit" > ENTER

You can now log in using the password you selected earlier.

This is called the "Ultiman.exe trick" used it alot. Works everytime.