Why my Samsung Tab T320 is suddenly sound through speakers and only through headphone?

[karvind]

When I purchased this it was all working fine. Suddenly it stopped giving noise through speakers and now i am able to listen only through earphones. Speakers are working as it gives sound for other notifications and alarms. When jack in headphones it does not show headphone plugged in symbol but i can hear through headphones and when i remove them speaker does not produce sound through speaker for music or movies. I dont know whats gone wrong with settings or some other thing? I have done 3 times factory settings but of no use. can someone help me to come out of this problem?