I have 2 email addresses. The App store uses email address 2 and I can't remember the password for that. Anyway I'd rather it used email address 1. I have checked through Settings>iCloud, Settings>iTunes & App Store and both are logged into email address 1. Settings>Messages was logged into email address 2 but I've signed out of that. Even so I still can't get the App Store to let me login with email address 1.
The easiest thing to for you to do is to go to the Apple ID management page and reset your password for your Apple ID associated with email address 1.