If you share your computer to your family or your friends, for some reasons, you should create an administrator account to manage the computer users, only those who has windows 7 password that can log in that account. And you need to create some standard users for them. Windows 7 has three kinds of account type. Administrator, Standard user, guest.

The standard account can help protect your computer by preventing users from making changes that affect everyone who uses the computer, such as deleting files that are required for the computer to word. A standard user can do almost anything that you can do with an administrator account, but if you want to do something that like installing software or changing security settings, Windows might ask you with a UAC prompt to provide a password for an administrator account.

If you have a Windows 7 installation disc, it's not a big problem for you to recover windows 7 password and log on your computer again if you get its password lost. Just insert the installation disc in computer and boot to the recovery options to reset Windows 7 password. What's more, a system repair disc that also enables you to access the recovery options. But the repair disk needs to be created in advance, before your password is lost.
1. Enter system repair disc in Start search box and hit Enter.
2. Select a CD/DVD drive and insert a blank disc to create the system repair disc.