Sometimes when I turn on my PC the DVD-CDR drive is missing. Other times it is OK. Have had an engineer check it out and he reckoned the drive might need replacing. He also suggested carrying out a scan and defrag which I have done. I have had the drive installed for 2 years. But why is it there sometimes and not others?

First try removing the Power plug and data cable (both ends of the data cables) from the CD/DVD drives and refiting them.

Next try deleting the drives from Device manager, and rebooting, so the operating system can load fresh drivers.

You could also try fitting new data cable/s.

Last resort would be trying a fresh install of the system.

colin.