well, we could tell you that you just need to browse the datastore, search your vms folders, and select the archive with .vmx, right click on it, and add to inventory. if you do so, you will receive a message that the virtual machine (name) already exists in the inventory. so you have to option to add it with a different name (it would be the name that appears in the inventory)
or, you just remove any VM (from the inventory, not delete them) , go to browse the datastore, and you can add them one by one, and start them all!!
regards
Jose Ruelas
Jose B Ruelas
http://aservir.wordpress.com