Why can't I see the red notification badge on my iPhone?

I just got my phone repaired for another reason and now I can’t see the red notification badge from the Home Screen. I mainly just need it for my mail and messages. I tried enabling and disabling the badge, restarting the phone, made sure I’m not on focus or airplane mode, and closed the app. I saw somewhere to delete the app, but as we all know you can’t delete these apps. So now I don’t know what to do. I don’t want to go back to get it repaired again but I might have to if it can’t get fixed soon.

[Re-Titled by Moderator]