OK, I understand now
Well...I would not remove the Vista install...just because an optical drive disappeared. Conversely, I don't see how changing your version of Windows will induce a possibly defective drive to work.
Since this is a laptop drive and I don't have any laptops...you need to wait for someone else to tell you how to go about troubleshooting this.
I will say...if the optical drive doesn't appear in your BIOS...both as an installed drive and as a boot option...it might be dead.
You may want to take a look at the 3d item on the list, http://repair4laptop.org/disassembly_acer.html