Hi udithawijayarathne,
We’re happy to provide some assistance.
Based on your original post, we recommend the troubleshooting steps via the link below since your display is not working as expected after updating to iOS 16.
If the screen isn't working on your iPhone or iPad
1) Restart your iPhone or iPad.
2) Make sure that your screen is clean and free of any debris or water.
3) Disconnect any Lightning or USB-C accessories. If your screen works after removing an accessory, try using a different outlet, cable, or charger.
4) Remove any cases or screen protectors.
We’re recommending the steps above because they directly address the issue you initially reached out to the community about, which is that your display isn’t working correctly on your iPhone after updating to iOS 16.
If the original problem persists after trying our suggested troubleshooting steps, provide us with specifics on what you see for more help, and we will continue from there.
Thanks for using the Apple Support Communities.
Cheers!