Ulli Hankeln over at sanbarrow.com also known as continuum created a nice little tool which recreates a VMDK descriptor file. When you end up with only a flat.vmdk this is a real nice tool. Ulli rulez :-).
Occasionally ESX VMs crash in such a way that the descriptor file of a vmdk gets lost.
If you ever need to recreate a descriptor from scratch but still have the *-flat.vmdk this little tool may come handy. Tool asks for a flat-file - like used by ESX 3 and Workstation. It ignores the CID and uses a bogus one. Output is named "newdescriptor.vmdk" - rename as needed.
Doesn't work for disks smaller than 1 Gb at the moment.
Via ICT-Freak