I don't know if I'm misunderstanding the question - but in the case the collector is offline you'll need to check the server and make sure the collector is running. You won't be able to start a collector when it is offline from the client, you'll only have the option to 'restart' when the collector is already connected (e.g. to put any changes into effect when necessary).
James, thanks for the answer, that makes sense. ends up someone may have changed some firewall rules so it won't connect. none of my admins can connect to it, so once we can that will be the next thing we check.