How to fix my headphones
I'd rather throw them away. There are a few Youtube videos that could help, though.

The one which felt into the glass of water was, perhaps, the right one? I don't know why, or if it is just mine (and my mother's, actually) but it seems that the left one sounds a lot lower than the right one. 

It seems, too, that Apple is quite nice about replacing the headphones while under warranty. It's worth trying, too.