The mouse-driven point-and-click interface provided by Windows is user-friendly and easy to grasp but, occasionally, and especially when things go wrong, you'll need to delve into the command prompt.
The command prompt allows you to issue precise text-based commands, which can be used to access software utilities that have no mouse-operated counterpart. For example, SFC /SCANNOW runs the System File Checker, and IPCONFIG shows the status of your network interfaces. The latter includes useful information such as your local IP address, which it can also renew for you.
It's simple to open a command prompt.
In Windows 7, click the Start menu and type command or cmd into the search box. Next, click the command prompt icon. The process is the same in Windows Vista; in XP, you should choose Start, Run, type cmd and press Enter.
In versions of Windows from Vista onwards, some advanced commands may require you to use an account with administrator privileges to work. In this case, you need to run the command prompt program in Administrator mode. To do so, simply right-click the command prompt icon and select Run as Administrator.