[MsNobleEleanor]

Are you able to login normally on a desktop/laptop okay? You might be able to change your settings as follows:

Settings and Privacy -> Security -> Two-Factor Authentication - turn this setting off or adjust it to no phone number option.

If that doesn't work. Try resetting your password and add a second email to confirm your account.

You could also opt in for email codes to verify who you are. Twitter emails you a code and you go to your email and you put the code in to confirm it's you on the Twitter app.

I hope this helps. Let me know if it doesn't and I can see what else I can think of that might fix this for you.