Error when restarting VM guest machine

HI,

I am not able to restart a virtual machine guest OS. Error which i am getting is " the guest OS can't be restarted because VMware tools is not installed, is not running, or is not responding.

Restart the guest OS from the console. Or reset the VM from the context menu or inventory menu."

Can any on help me to resolve the same.

Thanks,

Aditya