This article provides steps to power on virtual machines from the command line (either through the ESX host console or through the RCLI/vSphere CLI) if the host cannot be managed from vCenter Server or from vSphere Client.

ESXi 5.x

1. List the inventory ID of the virtual machine with the command:

   vim-cmd vmsvc/getallvms |grep <vm name>

   Note: The first column of the output shows the vmid.

2. Check the power state of the virtual machine with the command:

   vim-cmd vmsvc/power.getstate <vmid>

3. Power-on the virtual machine with the command:

   vim-cmd vmsvc/power.on <vmid>

ESXi 4.1

1. List the inventory ID of the virtual machine with the command:

   vim-cmd vmsvc/getallvms |grep <vm name>

   Note: The first column of the output shows the vmid.

2. Check the power state of the virtual machine with the command:

   vim-cmd vmsvc/power.getstate <vmid>

3. Power-on the virtual machine with the command:

   vim-cmd vmsvc/power.on <vmid>

Source : http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1038043