When I have forgotten my RAR password, a friend suggested me use Ainorsoft Password Recovery Bundle to recover lost my Yahoo password quickly! You can search it and have a try! 

http://windowspasswordrecovery.net/password-recovery-bundle.html

RAR Password Recovery 5.0 recovers passwords for RAR archives created with WinRAR, RAR or any other RAR-compatible software.

Forgetting a password for an archive created long time ago is a common annoyance. RAR Password Recovery helps you to get your data back.

Advanced dictionary attack, brute-force attack, and advanced brute-force with mask attack are used to recover the password. 

This software is easy to install and easy to use. All you need to do to recover your password is just to drag and drop your file to the program window. Dictionary attack supports 'mistypes' and additional user dictionaries.

http://www.recoverlostpassword.com/products/rarpasswordrecovery.html

RAR Password Recovery 1.1 RC17- a powerful tool to recover lost (forgotten) passwords:

http://www.brothersoft.com/rar-password-recovery-20658.html

RAR Password Recovery Magic will help.

http://www.brothersoft.com/rar-password-recovery-magic-208453.html