Headset problem the phone always detects a headset plugged in its port so everytime i call or racieve a call i couldnt hear a thing. but when a headset is plugged in it works perfectly. what could be the problem?

Check the bottom of your phone. There is a connector down there, is there any greenish stuff (oxidation) on it ? If so, the connector has been exposed to water. Clean the connector as well as possible, it might have short-circuited the pins and the phone thinks it has the headset plugged in. You might have to take the phone completely apart and clean it from the inside. If theres no greenish stuff on/in the connector, you probably have to visit your local Service-Center for repairs.