cant access App Store after changing email address

Did you properly change the email address associated with your Apple ID or did you create a new Apple ID?

Change your Apple ID - Apple Support

An App Store app is forever tied to the Apple Account used to acquire it (paid or free). The Apple Account is encoded into the licensed copy that is downloaded. It is in the copy's DNA. That is the only Apple Account that can redownload or update the app.

M1 Mac mini, macOS 14.6.1;  Watch, series 7 GPS/cellular, watchOS 10.6; iPhone 12 Pro, iOS 17.6.1; TV 4th Gen, tvOS 17.6; HomePods, audioOS 17.6 and Airport Express w/ Airplay 2

Please post a screenshot of what appears with the old "email address".

I'm not sure what to tell you.

It appears to me that that is the Apple ID associated with your App Store content and the Apple ID that you want to use is actually a new one.