Hello Pterrr,
It sounds like there may have been some liquid damage after losing your iPhone in the snow.
In these cases, you'll want to power down the iPhone and let it be for awhile to allow it to dry out. We wouldn't suggest putting it in rice to avoid additional damage to the iPhone (or the charging port).
If you power it on and still find this issue, then we'd take these relates steps to see if they solve this: If you hear no sound or distorted sound from your iPhone, iPad, or iPod touch speaker
If you hear no sound or distorted sound from your iPhone, iPad, or iPod touch speaker
If you can't hear a person's voice clearly, hear crackling, hear static, or have issues with sound quality, learn what to do.
Follow these steps
1. If your device has a Ring/Silent switch, move the switch forward—toward the device's display—so that orange isn't showing. If you're using an iPad, you can also swipe down from the top-right corner to open Control Center and make sure that Silent Mode is off.

2. Open Settings > Focus > Do Not Disturb and make sure that Do Not Disturb is off.
Contact Apple Support
If you checked the sound settings and your device still has sound issues, contact Apple Support to discuss service options.
If you want to try more steps on your own
If you prefer, here are some more steps you can try on your own. After following these steps, you might still need to contact Apple Support to discuss service options.
1. Remove all screen protectors, films, or cases from your device.
2. Check the speaker opening to see if it's blocked or dirty. On iPhone only, make sure that the receiver isn't blocked or dirty.
3. If necessary, clean the speaker or receiver opening with a small, soft-bristled brush. Make sure that the brush is clean and dry.
4. Go to Settings > Sounds (or Settings > Sounds & Haptics), and drag the Ringer and Alerts slider back and forth a few times. If you don't hear any sound, or if your speaker button on the Ringer and Alerts slider is dimmed, your speaker might need service.
5. If you hear sound, try making a call with your iPhone and turn on speakerphone. On iPad or iPod touch, make a FaceTime call. If you still can't hear, or hear static or crackling, then your network or reception could be the issue. Try to call again later, or from a different location.
FaceTime isn't available in all countries or regions.
Should it persist, then we'd recommend bringing it in for an inspection: iPhone Repair & Service As there may be a possible hardware issue.
Check your coverage using your serial number here: Check Coverage
Get prepared for your visit: Get your iPhone, iPad, or iPod touch ready for service
Select 'Service' here and search nearby for locations: Find Locations
Keep in mind the following: Water and other liquid damage to your iPhone or iPod isn't covered by warranty
Wishing you safe travels, take care.