OK, y'all. I've got news and info on this issue. After trying everything possible short of throwing it into the river, I figured it was def hardware related. I, of course prayed & am convinced that is the real reason it started working, bit jic here is what I did. I checked online just to see (I'm not an idiot, I wasn't going to take it apart. Well, probably not). But I was still all for slapping and twisting and flicking the heck out of it. Then, I decided to look at the other side of it. So I removed the battery and there is a tiny little slit-like hole there. I got out a safety pin and just kinda wiggled of a bit mostly toward the inside of phone. Lo and behold sound was working when I turned it back on. I can't believe it! I'm so happy!
Sent from my SAMSUNG-SGH-I997 using XDA
EDIT: It's easier to type on PC than on phone, so now I can make a short story even longer. haha. I should mention that this could be risky if done wrong, if that's not obvious for some people, and could screw your phone even more, so BE CAREFUL!!!
I'd consider using something flat enough to get in there, but not as sharp as a pin. I was just Macguyver-ing it. You do have to remove the batt cover, but don't need to take the batt out to get to the slit, but you may want to - in case of interference from metal pin and whatever. To be more specific to where this is: the external speaker is located on the backside of the phone - bottom, left. Duh, right?
Also, take this time to clean out any dust/crud that may have gathered in the tiny little cracks and corners, which accumulates more for those of us that remove the batt cover often, like putting phone in DL mode and such. Don't use alcohol or anything - this is a good place to use the pin or needle, and especially blow on it.
At one point, I had phone on and video going to gauge whether anything I was doing specifically was working or not. I never got sound to work that way, but it's still a plausible idea for someone else to try. Anyway, I hope this helps someone else out there. I like to include as many details as possible when I post stuff b/c it helps me when others are specific. So, let me know if this was helpful to you and good luck!