iTunes Producer unable to get password from my keychain
Looks like your Keychain has corrupted.

Do you get this error "Preferences Error: Could not load Accounts preference pane."

I have a solution here

Search for "Keychain Access" and a window as shown in the picture above would appear. Select the account which is troubling you.
Delete it/them and restart.
Moreover you can review any used accounts and remove them from here too.

Details here