Cell phone (camera) broken. Why is that? And how can I fix it?

Yesterday my Huawei p20 lite fell about 60 cm higher on the stone floor and shattered or the glass is broken. It still works and touch and display are ok too. (apart from 3-4 small green dots on the display that I can live with.

Today I wanted to have my display / glass repaired when I noticed that the camera app was not working. When I press the app icon there's a black screen for about 1 second. After that I'm back on the home screen. If I want to open the camera via Whatsapp or Instagram or Discord, nothing happens. I guess this is because the front camera is damaged because most of the cracks in the screen are at the top of the camera.

Now my question: Why doesn't the app even start when "only" the front camera is damaged? (Clear cache, restart etc. Have I already tried everything) And what can I do? Is there an app that only uses the rear camera? And of course the most important thing. Can I repair the camera so that it works again?

Remote diagnostics are usually not very helpful. And I don't know of an app that can only use one option. Everyone I know for it can be switched to front or back.

Factory setting, but will not bring much either.

Secure data.

I saved all data directly

Then try it.

Can I repair the camera so that it works again?

Sure, if you are familiar with microchip electronics and get the relevant components from China and have the appropriate equipment to disassemble the cell phone, that's for sure…

Otherwise, forget it and get a quote from a Turk repair center. In most cases (especially with entry-level cell phones), such a repair is not profitable anyway and you are cheaper to get a new cell phone right away.