If your vmware host machine unexpectedly rebooted due to power cut or any other reason, by default all virtual machines remain in powered-off state. To make them boot automatically perform following:

• Open vmware vSphare Client
• Select your vmware host and change to Configuration tab
• Under Software column click on Virtual Machine Startup/Shutdown, then click on Properties
• Check box next to Allow virtual machines to start and stop automatically with the system
• Arrange your virtual machines under Automatic Startup section in desired boot order

vmware ESXi 5.1