Cannot Start/Stop Services using SSMS 2014 (but 2008R2 works)
I can't reproduce that problem here, but my first suspicion any time a menu option disappears or becomes disabled is permissions. 

Since you've ruled out that your user can perform these features through other tools, then the difference must be the tool acting on your behalf. Right-click the SSMS shortcut (in some operating systems you'll need Shift+right-click) and choose Run as administrator.