My acer travelmate 240 wont read cd's anymore.

It is a pretty common fault when drive can not read one type - cds or dvds. That means you have to replace the drive. Price of the drive is not that high so that makes no sense to try to fix it. Cheapest I guess would be eBay (from what I see right now 20 dollars including delivery) but also there are plenty of on-line stores. Just use your favorite search engine to find the drive or simply go to the closest computer repair place and tell them that you want the drive replaced.