If the VM is still registered in vCenter or ESXi and the metadata is intact, use the built-in management tools: Overview of virtual machine snapshots in vSphere
The restoration of a VM from a delta VMDK typically occurs in one of two scenarios: the accidental deletion of a snapshot file leading to a broken chain, or the intentional need to revert a VM to a specific snapshot state without discarding intermediate data. The process is delicate, as delta disks are inherently interdependent. A delta disk contains only the changed blocks; it is meaningless without its parent disk. This hierarchy forms a chain—Base Disk -> Delta 1 -> Delta 2—where each link relies on the absolute integrity of the previous one. Restoring a VM effectively involves assembling this chain in the correct order, ensuring that the virtualization hypervisor can present a contiguous logical volume to the guest operating system. restore vm from delta vmdk
: A sparse file containing incremental changes. If the VM is still registered in vCenter