The audio sounded very bad and it sounded fuzzy

a few weeks ago my video audio sounds normal and i mean like videos that i take and when u hear it the audio sounds very HD and good quality. For some reason the next day when i record videos and rewatched it, the audio sounded very bad and it sounded fuzzy and sounded like it was underwater when it wasn't. And as i record again i tried to tap on the speaker but there wasn't any tapping sound and when i tap on the part where u plug in you headphone wires that is where the sound came from and i notice that the whole time i was recording the audio jack was where the speaker is but im also confused how it manage to happen like that when i used my headphones before that.. Please help me..