Hi all,
recently i've had issue of not being able to play any sound via the speaker on my 4s (be it ring, speakerphone, music etc). I've combed through all the forums and in the end figured it out. Here is a summary:
there are several possible causes.
1) Phone is on mute from the switch on the side: Simple but there were still some peeps out there who had this problem.
2) Phone is stuck in headphone mode due to debris: the solution being inserting and taking out the headset in hopes of cleaning the hole.
3) Phone is stuck in dock mode: once again due to debris accumulating in the dock/charge connector area. Clean/blow the area fixed it for a lot of people. By far the most common prob on the forums,
4) Bad circuit board connection: fixed by pressing down on bottom right of the phone. This only rarely worked for some ppl.
5) Phone messed up due to bluetooth. This was a rare problem but it was what happened to me. I recently got a new car and have been using bluetooth to place calls in the car. My speaker only stopped working after several days of pairing it with the car so it was weird. In any case, I fixed my problem by placing a call in the car, and during the call, changing the audio source to phone speaker (the phone gives you like 3 options, just look at the screen when talking). everything worked afterwards. I no longer use bluetooth in the car just in case.
6) other solutions that didnt seem to work at all for people was doing restart, hard reset, slamming phone (lol)