I'm sorry to say but you didn't really give enough description to fully diagnose what the problem is, but since I'm a bit of a newbie myself, I'll try my best
The majority of the time when a burner fails it's because the laser has gone kaputt, oftenly due to age, enviroment, or simply dodgy production. More commonly you may some really bad media - When you say it won't read or write, have you tried different brands of discs?
Finally, they're might be a problem with the disc manufacturer themselves. I don't expect you to understand too much, but cheap n cheerful media, tend to performer poorly than expensiver media. Note though that the brand of disc doesn't illustrate who manufactured it - 99% of the time it will be produced by a third party and sold under their name.
Memorex, for example, can be produced by Ritek / CMC Magnetics / Moser Boar India - They are unreliable because they switch manufacturers now and again, and often get bottom of the barrel grade media. Memorex, along with other cheap brands, also typically had the problem of power laser callibration errors - Meaning that the laser simply could not calibrate successfully enough to burn a disc. (Datawrite Titanium CD-R)
I know for example my old Pioneer burner would only give 50/50 burning success rates when I used Bulkpaq / RiDisc DVD-Rs - Anything CMC Magnetics would berk on my discs. The same for CDs, however, would be perfectly acceptable. Weird.
Also we would need to know what program you are using and preferably what write speed you are using, along with what brand, if possible. Certain brands are preferred on certain burners :iagree: Finally, from what I know it's either some naff media you have - Simply buy another brand - Or your drive might be dead/dying. (Laser gone on it).
Can I interest you in a OEM (i.e. No cable or screws or software - But if it's a replacement, this shouldn't be a problem, simply use the existing screws on your current drive) SATA Sony DVD burner? Currently, it's the cheapest going on Amazon for a shade under Â£12 brand new
http://www.amazon.co.uk/Sony-AD-5260S-0B-Internal-DVDRW-Black/dp/B003Q8ZZ3U/ref=sr_1_1?ie=UTF8&qid=1301919579&sr=8-1 (Currently out of stock though :doh: )
If you like the older variety, PATA - Then bag yourself something like this
Failing that, you might be able to pick up a cheap one on a market / eBay somewhere