How you had taken backup of VM?
if you have simply copied or exported VM on Local Disk you can upload VM in Datastore and add it to inventory.
if you had used some backup tools and backup files are not in vof or .vmx, .vmdk format then only you need to restore it using backup tool.
for the file locking issue, make sure vmdk or .vmx file is not locked by any Host or its not being used by any other VM.
if you have just uploaded VM folder, then Browse the datastore, locate the that VM folder and try to delete .lck files from VM folder.
Below KB, can you help you to find the Host which has locked VM files.
VMware KB: Investigating virtual machine file locks on ESXi/ESX
VMware KB: Finding the lock owners of a VMDK or file on a VMFS datastore in VMware ESXi 5.5 P05