Hi musiclady. It certainly sounds dead to me. Fortunately keyboards aren't expensive. There is a good range at reasonable prices, have a look at E-Buyer click here, but don't forget to add the poastage!
Have you tried tipping it upside down and shaking it ? It may sound daft but keyboards accumulate a load of grot inside if not cleaned out occasionaly, a blast with a compressed air duster may not be a bad idea if you have one.