My stereo speaker doesn’t work right...
So one day I woke up and realized that my stereo speaker(The one where the old microphone was) is all crackly and muffled. Is there any throubleshoot, or fix for this?
If you're talking about the "speaker" at bottom-left of your iphone... that's not a speaker, it's a microphone.
If you're talking about the earpiece speaker, try to gently clean it with a smooth brush.
If nothing changes, have your iphone inspected at the nearest Apple Store:
Apple - Find Locations - Location Selector
Regards
Giulio