i'm stuck in headphone mode

What do you mean you used water eject? What is that? It sounds like you have water damage to the phone. Make a Genius Bar appointment and have the device checked for damage. Be prepared to pay for it. Water damage is not covered under warranty.

I've never seen a method in iOS to eject water from an iPhone. I'd like to see that Setting. There is a water eject on the Apple Watch, but not the iPhone. No matter, with the phone stuck in headphone mode, you need service from Apple.