Wi-Fi connecting issue , disconnects abruptly

When i am connected to my home Wi-Fi, after some time the Wi-Fi disconnects automatically ! And when i try to reconnect it that doesn't connect , it only shows saved below the router name but doesn't connect . After restarting or turning on/off flight mode sometime manages to connect my phone to Wi-Fi again ! My phone also hit the floor yesterday , this issue was never seen before that !