my iphone is frozen after upgrade software on the open mail app

1. Fully quit Mail app via the App Switcher screen.
2. Reboot your iPhone.
3. If app is still misbehaving, in Settings app, go to Passwords & Accounts and toggle of Mail on every account where it's on.
4. Open Mail app. If app is still misbehaving, complete step 5, otherwise go to step 6.
5. Delete the app, reboot your iPhone and reinstall the app via the App Store.
6. In Settings app, go to Passwords & Accounts and enable Mail on only one of the accounts; test if Mail app is still misbehaving.
7. Repeat step 6 for another account. If you find the issue is back when specific account is enabled, you might need to delete and re-add that specific email account.

gjunonia wrote:

how do I stop the mail app iPhone open in mail app then frozen I can slide from left to right and see mail app but nothing happens when I touch it

How to force an app to close on your iPhone, iPad, or iPod touch https://support.apple.com/en-us/HT201330

If your iPhone, iPad, or iPod touch won't turn on or is frozen - Apple Support

Do you see all your recently opened apps? If yes place your finger on the mail app (don’t push it) and slide up.