Q: Why the screen does not light up on unlocking the phone? It never did!! Moreover, the screen dims suddenly while using the phone!!

Greetings Mahmoud Basyouni,

It appears you are experiencing issues with your iPhone display. That does sound troublesome. The following article provides information you may find useful:

Get help with the screen on your iPhone, iPad, or iPod touch - Apple Support

If your screen is too dim, too bright, or you see only faint images

 

1. Try to adjust the brightness. If the screen doesn’t respond when you adjust the brightness, open several apps to make sure it’s not an issue with only one app.
2. If you have a screen protector, try removing it. Try removing your case if it includes a screen protector.
3. If you see the issue in multiple apps, restart your device.
4. If restarting doesn’t fix the issue, restore your device.
5. If you still see the issue after you restore, contact Apple Support.

Thank you for contributing to Apple Support Communities.

Best,

Bobby_D