To restart IIS using the IISReset command-line utility
1.From the Start menu, click Run.
2.In the Open box, type cmd, and click OK.
3.At the command prompt, type iisreset /noforce computername, and press ENTER.
4.IIS attempts to stop all services before restarting. The IISReset command-line utility waits up to one minute for all services to stop. If the services cannot be stopped within one minute, all IIS services are terminated, and IIS restarts.

example :

source :
https://www.microsoft.com/technet/prodtechnol/WindowsServer2003/Library/IIS/003ed2fe-6339-4919-b577-6aa965994a9b.mspx?mfr=true