How to fix my iphone 5 speaker?

Yea well this is going to sound so stupid but I was sitting next to my little brother and he was eating, he grabbed my phone off me and it slid down onto his place right into tomato sauce.
I managed to get it out the charger and earphone bit but my speakers are dead crackly and not as near as loud as they used to be.
there's screws next to the speaker so would this open it up? It's the speaker at the bottom at either side of the charger slot.
shall I take it to the apple store? If so how much would this cost?

Yes take it to the apple store. It would cost like $4oo because they give you a refurb. They don't actually fix it.

I sent mine into http://www.appletreecanterbury.com

It was really cheap and send it back really quick. Only cost me £5 to post it back to me