My friend recently bought a Sony Vaio laptop with Windows 7 pre installed. Don’t know what he did, he called me up and said he forgot the password and couldn’t login into the system. I was sure I could do something if it was Linux, but Windows I was not confident, anyway I told him to bring it, so I could see what I could do. After some serious search and I found this tool Offline NT Password & Registry Editor , which gave me the needed solution. Here is a good step by step guide for using this tool - How to Remove Passwords Using Offline NT Password & Registry Editor. So next time you are in same situation don’t worry, you can login without making any destruction to your old data.