amd Kaveri A10-7860k PCI CMI8738 no sound Ubuntu16.04

My desktop pc: Processor amd 64 Kaveri A 10 7860-K 3600Mhz. Radeon R7 Motherboard ASRock FM2A68M-DG3+ The sound card is a PCI CMI 8738. My OS is Ubuntu 16.04. Don't know if some of that information is relevant; sorry if not. Unfortunately i've got no sound but scracht and (sometimes) the sound from miles away behind the scratching, and practically silent. I'm new with Ubuntu and Linux in general, and my theoretical resources are poor or directly don't exists. I've tried to discover some solution in forums but no one worked in this particular case. In adition my language is spanish, but i'm trying in english because i know there must be many more users between english speakers. I'll be grateful if someone could give me a solution, because i'm running out of options: buying new pc (no money) or return to window$ (which I would hate). I love music but now I've got to get along with my phone; considering I've got not less of 300 Gbytes of music files but can't listen to them, you can imagine that I'm not happy. Sorry for my horrible english. Please help! S.O.S. mayday!