Password Incorrect Error on Itunes

Hello friends,
I have a problem here opening my IPod files using ITunes, whenever it ask for a password, I get an error of Incorrect password. Click OK to try again, attached below the screen shot of the error.
Incorrect password. Click OK to try again.
I am wondering why I get this error message, while I am sure I typed the correct password. I am also thinking if there any virus that will corrupt the stored password in my computer.
Please friends help me with my confusions about the virus, and also are there any ways to retrieve my password just in case, I forgot the correct one.
Thanks.
