I changed the administrator password. Since, when I start or restart Win7, I get a message saying that login or password is incorrect. I have to type in the new password each time.
Can somebody help ?
Where are you getting this message? At the Welcome screen, after you try typing in your old password? If so, then you must have changed the password for that account (which would make sense if your account is the Admin, since that's the password you changed.)
If that isn't what you meant, I apologize - could you try posting a screenshot of what you're seeing?
So you have to clear the password regardless if it is Administrator or a normal user password. Just rely on SmartKey Windows Password Recovery. The good thing for this software is that you can use it in future on any PC to remove or recover any password, most other software have a limitation that you can use it only once on 1 PC.
You can get the software from recoverlostpassword.com website