There are so many issues we seen while the Virtual machine becomes "Grayed Out" and inaccessible through vCenter or any other way. Now the question is how to bring it back in the previous condition. Follow the steps as shown below to get back your orphaned VM.
Scenario: The virtual machine is grayed out and in vCenter server and started showing orphaned.
To bring it back online please follow these steps.
Note: Before doing this task you must note down the orphaned virtual machine Name, Host/Cluster Name, Resource pool if any, Datastore, Virtual machine folder path in Specified datastore, as it will be required while adding them back to the vCenter. Also remove the orphaned VM from inventory of the vCenter by clicking on “Remove from inventory”.
1. First of all select the Orphaned VM and find the Datastore & the folder of the virtual machine where it resides. In this example its "Datastore1"
2. Now go to the specified datastore by selecting the configuration> Storage option on vCenter server or ESX (in case of standalone host).
3. "Right Click” on the residing datastore and click on "Browse Datastore".
4. Go to the specified folder of orphaned virtual machine and select the .vmx extension file followed by the virtual machine name and select "right click > "Add to Inventory".
5. After Selection it, It will open "Add to Inventory" wizard. Now provide the Name of the original virtual machine, Vcenter name, ESX Host details, Resource pool, and it will finish the wizard with the summary details.
6. Now you can verify all the details of the virtual machine.
Hope this post has helped you in dealing with issues of grayed out VM's in vCenter Inventory.