external dvd drive/burner not recognised, have a hp dvd840

[Doc49]

this dvd burner was installed and worked correctly untell I had a "bug" took it to a repair shop and they had to reformat, everything else works fine after being reinstalled. ie mouse,keyboard, two printers. all are usb. the dvd will only show up as unrecegnisd device. I thought maybe the burner was bad so bought a new one which is sold under the name brand of ativa
it is exactly the same as hp it does the very same. have downloaded drivers from both hp and ativa neither will load and work with the drives. by the way these are external drives. Also was online with dell they were unable to correct the problem. HELP

[Kevin_gibson]

When you connect your external drive to your PC, do you get any new hardware messages on your screen? If you do, the PC is recognising the HW. If you don't, it could be a faulty part (or connection) Or it could be some fault on your OS.