I pressed volume up, volume down, right button for 12 sec, apple logo appeared but nothing else changed. What can I do to not have that black screen. Please help.

(1) Try and Force Restart your iPhone EXACTLY as shown below and see whether that resolves the issue:

• Press and quickly release Volume UP button
• Press and quickly release Volume DOWN button
• Press and Hold the SIDE button until an Apple logo appears and then release the Side button (Can take up to 20 seconds. (DO NOT release Side Button when invited to Slide Power OFF). 

(2)  If the above does not work then - Follow the instructions in this article by Apple ➔ If your iPhone is Non-Responsive or Frozen and see if that helps.

(3)  If that does not help your phone might need service ➔ Contact Apple for support and service - Apple Support

Axel F.

If you have access to a PC with iTunes, or a Mac, try connecting your iPhone to it with your charging cable.

Windows user? - Download iTunes here: iTunes - Apple

Once your iPhone is connected, follow Axel Foley's guide:

Volume UP release, Volume DOWN release press and hold the POWER button until you see this on your iPhone screen:

On your computer, a pop-up will appear where you can select Update and Restore.

Since you're supposedly on iOS 15, tap Update.

Odzulia Said:

"I already pressed volume up, volume down, right button for 12 sec, apple logo appeared but nothing else changed. What can I do to not have that black screen. Please help."

-------

Troubleshooting a Frozen iPhone:

Tried this Link?: If your iPhone is Stuck on the Apple Logo - Apple Support

Did you follow the instructions in steps 2 and 3 listed in my original response?

Axel F.