What does “reset all settings” do on the iPhone 7 Plus

My iPhone 7 Plus has fell while I was listening to music and I was using an adapter with my normal apple earphones because I don’t have to earphones for the phone, well when my phone fell face down the adapter was still connected to the phone but my earphones were not and when I connected the earphones back they didn’t want to work anymore I tried it with another pair of earphones and adapter and it still didn’t want to work then the mic on my keyboard doesn’t want to work and when I get calls I either can’t answer them or I could answer but can’t hear anything and they can’t hear anything from me the speaker button also for some reason doesn’t want to show with the calls my brother has suggested to do a “reset all settings” but I dont Want to lose my pictures, messages, apps, mail, iCloud id ect. So that’s why I’m asking what does the ”reset all settings do”