Hello 2043,
Thanks for using the Apple Support Communities. We understand that you're having an issue with the keyboard on your iPhone. When you say it's not working, what's the exact behavior you're experiencing? If it's touch related, do you have issues on other screens using your touch display? Have you had a screen replacement performed on your iPhone?
How many keyboards do you have installed on your iPhone? If you're unsure, check out article, Add or change keyboards on iPhone for direction.
Once we have more details about what's happening with your on-screen keyboard, we'll be able to narrow down potential troubleshooting options for you try. Please follow up at your earliest convenience.
Best regards.