To start a service: net start <service_name>
To stop a service: net stop <service_name>
To get the list of services installed on the computer, open the registry (use regedit) and navigate to HKLM/System/CurrentControlSet/Services. In there you can see the list of services: one entry per key.
If you want to restart a service from a batch file, you have to wait before restarting it as it can take some time to stop a service and the net stop call is not blocking. You can use the following to restart the DNS Client service for example:
:start net start Dnscache if not errorlevel 0 goto start
This is a crude example, it will loop indefinitely if the service fails to start for an unkown reason.
For other registry tips for french readers: Astuces Regedit