The obvious first thing to do is check your connections.
Even if they seem tight pull your data and power plugs out and reseat them.
Then power the computer on and enter your BIOS usually F1,F2,F10 or delete while starting before windows screen.
Look under section of BIOS menu for hard drives or storage and see if CD/DVD is recognized there.
If it is recognized there restart using ctrl-alt-del and then boot into windows.
If it is not recognised now then you might need a driver though usually XP has drivers for almost all drives.
Check the drive's manafacturer's website and download and run driver.