My iPhone wont turn on

I have my iphone 4 once it dropped to floor & then after some time i noticed that it turns off, then i plugged it to charge pin. it started but shuts off after showing the apple logo . then after some days i plugged my iphone to charge it starts but it only works if i keep it plugged to charge pin . if i remove it from charge it will shut down , when it starts it will vibrate and after 1 min it shutdown & starts i have my data on it & i never take a backup , i restored all settings from the settings but the process is repeating then i hold both home & power buttons for the same time at that time i lost my data , some one plzz help