When I load a dvd into my sony 5 disc player it says "reading" but fails to play. I have tried a variety of discs so I know that the discs themselves are not the problem. Help.

Might be.

use soft cloth to clean the disc.
Examine the disc for any cracks or scratches that might be interfering with playback
Attempt to play another disc.
If another disc plays in the DVD player, then the previous disc is faulty.
If still the same. try to unplug for 3 hours. if the same. check sony.com/repair for service option

This is quite common of older players. Some only work with DVD+R discs and others with DVD-R discs.
Some player also does not read recordable discs (an early form to try prevent piracy)
Also make sure if recorded on your Recorder, that the disc is finalized before you try to play it on an older player. (See your menu / manual on the recorder for the procedure)

With the large variety of video formats available nowadays it's difficult to find a unit that plays them all. Chances are you want to play a movie you burned yourself, and though it plays on your PC, it will not play on the DVD player.
Try playing the disc on your PC, and then try different DVD units, perhaps pretending you're shopping for one and want to try your own movie. Chances are these new units may NOT play it either, perhaps because you're using DivX or Xvid two video format contenders on the PC because their codecs offer great compression and very good quality (small file size and even HD video).
If it works on your PC it's because you may have the latests codecs (codifier / decodifier) installed, since some of them may have installed themselves as plugins for your browser, or come as part of a DVD viewing program you may have installed, like WinDVD.
For the time being, watch the DVD on your PC and upgrade your player, if it's more than 2 yrs. old.
Good luck!

After variety of different tests and findings I have resolved this issue. It appears that the DVD burner was not in good working order and the DVD player was not at fault. Thanks you to all who answered and responded to my problem. Many thanks.

try different discs, sounds like it doesn't like the media.

Its due to faulty Laser Lens/head. Try cleaning it by cleaning CD. If still the problem persists, contact near by service center.

it may be the problem you told go to service station may be lance has been faulty.

Stumpy, I think the first step could be to find out between the DVD player and the disc which one has a problem.If the DVD Player is able to play other discs then it is possible the problem is with the disc only. If that disc can be played quite alright in other DVD players then the problem is with your DVD Player. I suggest you trial that first. I think the indication of " No disc insert disc" could be that your DVD Player is failing to load or read the disc either because the disc has some scratches or because your DVD Player lens are not powerful enough. I am, Letsthank.

Try the disks in another DVD player. If they play with no problems in another player, then you have a hardware issue with your Sony. Nowadays, if it is out of warranty, fixing it is not worth it, because it is cheaper to replace, at least in the USA.