iPhone 7 Plus randomly wouldn’t let me do things? My iPhone 7 with iOS 11.3.1 has a problem with its microphone and headphone jack.

When I make a call, I am unable to click on the loud “Speaker” button, and also am unable to hear the person on the other side of the call. They also aren’t able to hear me. Basically my phone can make calls, but I am unable to hear the other person and the other person can’t hear me. Also my speaker DURING calls is greyed out, so there’s definitely an issue with the microphone, as if it was disabled.

Additionally, my headphones cannot be recognised by the phone when plugged in, however the phone is still able to charge. I know for a fact that the headphones are not faulty, it definitely has to be a phone issue. 

I still have three months left on my warranty before I can get a new phone, so any help will be deeply appreciated!

-Cambria
Being unable to hear through the speaker and the speakerphone button being grayed out are symptoms of a hardware failure with the device.  The troubleshooting you could try is: 


Force restarting the device - Do this by holding the power button and the down volume button together for ~10 seconds.  When you see the Apple symbol let go of the buttons. Then test to see if it's working.
Reset settings - Under Settings> General> Reset, select 'Reset All Settings'.  After the reset test to see if it's working.
Perform a restore - Backup you device before doing this step using iCloud or iTunes. 
Best way to do restore is by connecting to a computer with iTunes, then performing the force restart steps, holding the buttons slightly longer until you see the iTunes symbol show on the iPhone screen.  Then follow the prompts in iTunes.  Once restore is complete setup as new if possible then test again to determine if issue is still happening.


Since your device is still under warranty I recommend contacting Apple Support.  They will make sure you have completed all necessary steps and if the issue is still occurring be able to present you with replacement options.