You can create a new VM (PowerdOff) with a new disk. Then browse the folder of this new VM to change the VMX file tags. You need to change the path of VMDK like this:
scsi0:0.filename = "NewVM.vmdk"
change it to:
scsi0:0.filename = "OldVM.vmdk"
and after you saved your changes, put that new VMX file into the old VM folder and rename it. if you had more than one disk on the old VM, you can use the tag for every VMDK file separately:
scsi0:1.filename = "OldVM1.vmdk"
scsi0:2.filename = "OldVM2.vmdk"
I hope this can be helpful