Forgot password

I have forgotten my Password for loging on to the account but since it's saved in my Computer I can Log on But when I wanted to change the password I am facing a lot of problem since I have forgotten the password.
My BB bill for the month of AUGUST 07 is so high that I think my line is being
used up by somebody else. So I immediately want to change my password.
Please do the needful as soon as possible.

The above is an e-mail sent to me from some visitors but no idea what he or she wants me to do about it...