Speaker problem on Nokia Lumia 830/Windows 8.1

[stbel55]

The speaker which also acts as the ringer is very intermittent!! I researched and found that one issue is the headphone jack shorting making the phone think I'm using heading headphones and disconnects speaker! I've tried plugging in headphone jack multiple times and I found sometimes this does bring speaker back on?? I discussed problem with store where I purchased and they told me they would send phone out for repair but back up my stuff first! ( All they will probably to is reload the windows 8.1 again. I personally don't think It's a hardware problem!!) Has anyone else had problem and if so what was the fix? Thanking you in advance.