My iPhone 7plus mute and un mute button is not working and I drop it in the pool

Hello,

It sounds like your iPhone has water damage and may need a repair. Follow these steps:

If the volume buttons, Ring/Silent switch, or Side Switch doesn't work

On an iPhone, the volume buttons and Ring/Silent switch are on the left side of the device. The buttons on other iPhone models are similar. On an iPad, the volume buttons and Side Switch are on the right side of the device.

If any of these buttons or switches don't work, follow these steps. After each step, see if you still need help:

1. Unlock your device. Some buttons don't work from the Lock screen.
2. Check for debris or dirt around the button or switch and clean with a soft cloth.
3. Remove all protective films and cases that might interfere with the button or switch.

If the button or switch still isn’t working, is damaged, or works intermittently

Contact Apple Support, then follow the steps to complete your service request.

From:

Get help with buttons and switches on your iPhone, iPad, or iPod touch - Apple Support

If you dropped the device in the pool and the button is not working, then make an appointment at the Genius Bar of the nearest Apple store and see about an out of warranty replacement. There will be a cost involved, since water damage is not covered under warranty.