How to restart service using command prompt?

You can use sc start [service] to start a service and sc stop [service] to stop it. With some services net start [service] is doing the same.

But if you want to use it in the same batch, be aware that sc stop won't wait for the service to be stopped. In this case you have to use net stop [service] followed by net start [service]. This will be executed synchronously.

You could create a .bat-file with following content:

net stop "my service name"
net start "my service name"

net.exe stop "servicename" && net.exe start "servicename"

To restart a running service:

net stop "service name" && net start "service name"

However, if you don't know if the service is running in the first place and want to restart or start it, use this:

net stop "service name" & net start "service name"

This works if the service is already running or not.

For reference, here is the documentation on conditional processing symbols.