Just in case this is your development server and you are using an EDN/Dev-license.
Ours just expired this morning on our dev box, and we had the same behavior. I did a reboot, and then none of the services showed up (but the folders still did...strange). I had thought I had re-authorized using the 10.1-10.4 authorization already (a month ago), but for some reason, it/I had only grabbed the Portal install. Keep in mind that the 10.1-10.4 authorization for AGS/Portal is different than the 10.5.x Enterprise authorization.
Going into myesri, Developer, I created a new authorization file (after viewing what has been provisioned) for 10.1-10.4 AGS. Then, using the .prvc file to reauthorize fixed the issue (but restarting my AGS again just to make sure). And now that I think about it, after the reboot, the Windows Server Manager did not show that is start. Now it does.
BTW - when I looked at the logs in Server before reauthorizing, I had a bunch of errors like:
Funny, I always know the expiration is coming (and thought I had already fixed it) but it still catches me off guard sometimes....makes me thing my privileges were changed by IT or the likes.
BTW - the reason I even looked/researched is I was trying to use "View cache status" on a service that appeared to be started, but it was grayed out. That is, just weird behavior, but no real red flag.