upload your wallet.dat here :
https://blockchain.info/wallet/import-wallet and try to login using your password that you remember.If you are able to login then you can find the prv key in the settings of your wallet.Hope that it helps.
That site no longer works.
Op, unfortunately, it is very difficult to recover the password. There are services that can recover your wallet password, but be careful because they can sometimes steak you're money if you give them too much information. There is a way to send them parts of your wallet so that they can get the password but not all of the private keys.