I think I may have found the solution. It may or may not fixed your but definitely worth giving it a try. It works on mine. Let me know if this helps you too. and pardon my english.
I was having the similar issues like you guys are having - no sound from speaker (except alarm) after screen replacement. Audio from headphone jack is ok.
See this metal shield/cover below?

Now look at the main board section below where this metal cover is supposed to go.

You see those eight shiny components that I've marked with the red circles. I didn't pay any attention to the placement of the cover when I was first putting it back together. I just lay the cover in that area and secure it position with the tape. However, given a little bit more thought, I think the metal cover is not supposed to have direct contact to the main board, especially when there is something that looks like exposed ground traces in the proximity. I took a better look at those eight shiny components and it turns out they are stands (with a slit in the middle) which I guess is suppose to hold the metal cover in place but lifted above the main board. I make that change and (voila!) now everything is back to normal. That nice unlock click from the speak have never sounded so nice.
Christexaport and JJ14x - you two are very annoying but I do hope you fix yours too (assuming Christexaport haven't sold his yet).