I cant join my friends world, ( server is searched )

Im playing with 2 friends since 1-2 weeks, we never had problems but since yesterday i tryed to join my friends world and there stand, ( searching server ) and im not joining the world. I tryed everything and it didnt work. When i click on the world i am joining the game but on my screen is just the loadingscreen, im standing in my house and my friends cant hit me said my friend. I really need help