My DVD drives aren't working

Hello,
I'm running a windows 7, 64 bit system. I've got a dvd drive that was working last week, now it won't play anything & doesn't show up as a drive on my computer. If I go to device manager, it is listed, then If I go to the properties of the drive, it says that windows can not load the drivers for this device. The drivers were fine a week ago. I bought a new DVD drive & installed it & the same thing happens. Any ideas would be appreciated.