If you do no thave a WinPE disk, shut the VM down - then from a different VM, go edit settings - > Add Hard Disk . .and follow the wizard to add a disk (making sure you add an existing disk)
You'll need to specifiy the vmdk file that points to the faulty disk.
Once you have got the disk added to a new VM, you could follow the same process as before (except of course that you'd need to specify the disk number for the disk you are adding)
When complete, you'd then remove the disk form that VM (not delete) and re-attach to the faulty VM and start it up
You may also need to edit the boot.ini file if you had an additional partition before (though hopefull you'll be OK)