Hi there, cariyon! Thanks for reaching out to Apple Support Communities.
After reviewing your post, it sounds like you are running into some Mail issues on your iOS device. We definitely understand that can be a concern and we'd love to help. Let’s start by reviewing a couple of websites.
First, if you need to add or remove a Mail account on your iOS device, these steps will help: Add an email account to your iPhone, iPad, or iPod touch.
If you continue to be unable to sign into your Mail, you may need to reset the Apple ID password, if that is what is stopping you from signing in: If you forgot your Apple ID password.
Please let us know if you have follow-up questions about this issue, or if the issue remains unresolved. Have a great day!