Welcome to the Nokia Forums and thank you for your post.
The touch screen issue you're describing can be fixed with a software update. Connect your phone to Nokia Suite and click on the green arrow where you will be able to see the available updates for your phone. If no update is available, please reinstall the current software. The option to do this is displayed in blue.
Please get back to me to let me know if you manage to resolve your issue, otherwise I can provide further support.