It seems u have to spend this millenia hackin the password, hacking passwords,esp. RAR, (the longer it is, the longer it takes (exponentially)) takes up a lot of chip power and time (read 100s of years); even with the best password recovery sw!!!
And downloaded password encrypted compressed files are mostly rar...
Hey!!! If it's a known word (not name or so) then there is a way out. U get dictionaries, word lists with some Password recovering sw for dictionary attack. They could speeden up things to about 1/2 an hr. Or the password has to be small (max of 4 letters). That is ur only way out. Anything more takes infinity.
U might need a grid of supercomputers to get this done with asap
IF U WANNA HEAR FROM THE EXPERTS : GO HERE;
RAR archives are encrypted by the much stronger AES-128 standard; now READ THIS
HERE
AND HERE (might relieve u a bit)
HELP ON PASSWORDS
A better idea will be to dump the file.. collect new ones...
For ur happiness & experimentation... try these
Advanced Archive Password Recovery
RAR Password Cracker
Rar Key
Try this too
(Psst) Tip: Most of the times, the password will be the site name (full name) or owner names... Don't say it to anybody )