I think you should get a new one. You can e-mail Nintendo about your problem.
Click here to E-mail Nintendo about your DS problem If you think you want to get it repaired call 1-800-255-3700. That is Nintendo's number for repairs. Or if you do not want to send it for repairs you can find your DS problem in this link.
Clicky If you decide to send it for repairs,then youcan track your order in this link.
Right here When you call Nintendo they will give you a tracking number. Keep it somewhere safe so you won't forget it. Also, when you call them they let you decide what color you want your Nintendo DS lite to be. The repairs cost money, but less money then getting a new one. I had my DS since 2006 and they still accepted it. They renew it like a new DS. It doesnt come with the Stylus. They also ask for the number code on the back of the DS. It's ok if you don't have the code anymore. They still send you a repair it. You don't need to be a member of Nintendo.com to get repairs. They give you 3 options. I forgot what they were but each of them are different prices. Good Luck!
Hope I helped.