i can’t get into my email. i sign in but it tells me it’s already on my phone. but it won’t let me into my actual mail.

Try a restart.

Restart your iPhone, iPad, or iPod touch         

Try a forced restart.

Reset Device.      

If necessary

Hard reset.        

Do a backup and try a factory reset. Then restore from your backup.

Restore to Factory setting.      

Backup - Restore your device from an iCloud or iTunes backup.      

If you are trying to access the email account, does it show in Mail?

Have you checked Settings/Passwords & Accounts to see if the address is there and enabled?