iphone 4s speaker not working (mostly)

My speaker quit working. Well, mostly. It works on speakerphone, and when I get a call. Text tone is intermittent. Something similar happened a couple of weeks ago, and it said it was in Headphones mode. Now it doesn't say that. The audio does still work from the headphones jack, but stops when it is unplugged, and the volume indicator disappears.

Last time I read that if you played some audio with the headphones in, then unplugged them, the speaker would work. It did. It's not working now, and the behavior is not exactly the same, though similar. Seems like it has to be software since the speaker does work when there is a phone call. It just does not work when I want to listen to something other than a phone call.

I resisted the ios7 update but am downloading it now, hoping that might help. It's still under warranty, so I have that going for me. But I live in a remote part of Alaska and would rather not be without a phone for however long it takes to get service.

Thank you in advance.