As far as I know there a are a lot of ways to solve your problem and the easiest one of them is to use program designed to see to such problem!
And I have tried many of them, according to my experience, I recommend you the password recovery bundle which not only can recovery your RAR password but also other files' password.
And I google the address for you. it is
http://www.recoverlostpassword.com/p...drecovery.html
Wish you good luck.