Hi
Go to iCloud make sure iCloud back up is on Then backup now over your wifi.
Have you got enough space for download you need 4/5G to download over your wifi
If not turn iPhone off Make sure your pc is running the latest iTunes 12.8 or later.
Connect lead to USB on your pc Press just the power button down on iPhone don't let go Connect lead to iPhone keep power button pressed down until pc sees iPhone Then wait for restore you may need to do this more than once Before it works.
Cheers
Brian 🇬-1F1E7;