ICloud :: Forgot Password For Account In Apple Mail?

I don't know why but a recently I've been asked to enter my icloud password related to my iCloud e-Mail address. stupidly, I've forgot what my password is. is there a chance to reset it somehow? 

To explain the situation a bit better and what I've tried already, here a short discription of the situation: 

- I do have a appleID that is called firstname.lastname@gmail.com the related password is appleID_Password1.

with this combination I also conduct my purchases in iTunes and the AppStore. But to rule this possibility already out: It doesn't let me access my iCloud eMail account in Apple Mail. Funny enough, though, when visiting iCloud.com this is the combination with which I log onto iCloud incl it's mail service within the web browser. 

- the iCloud eMail address for whose password I am looking is called something like abcde@me.com. I have implemented it into my Apple Mail program running on Mac OS X Lion. Since setting up the account i've never ever been asked to enter my password. But now, out of a sudden, I was. And, of course, I couldn't remember it anymore. Hence, I don't receive any eMails sent to abcde@me.com anymore on my mac. 

Can somebody tell me how to fix it, if it is not the password for my appleID??

Info:
MacBook Pro (13-inch Mid 2010), Mac OS X (10.7.3)