Restarting the VMware management service can resolve lots of problems mainly problem where the VMware Host cannot be contacted correctly by the vSphere Client, or a Virtual machine will not start or vmotion
Restarting the service does the same things as restarting the host but done properly it leaves the Virtual Servers running!
To restart the Service Console
1) Connect the Host in question using SSH using PUTTY or some other SSH software or be physically in front of the Host
2) After logging in if you connected to the host using SSH enter the command su -l to change to a super user, enter your root password when prompted.
3) To restart the service enter the command service mgmt-vmware restart after a few seconds you will see the service being stopped and started.
It may take a min or two for the vSphere Client to register the change, so be patient