There are quite a few keys not working on my keyboard. There are no sticky or dirty keys, I think it's just getting old....

The RAM can be replaced, however. If for some reason there's a problem with the ram that's installed, you will be able to replace it. But like oldturkey03 said, only with another 2GB stick of RAM.

If the audio jack is not able to be replaced or repaired, a possible solution to get sound is to buy an external USB sound card which will replace the malfunctioning audio jacks.