Everybody has to come to an end one day so death indeed is inevitable. Nobody can give u one hundred percent guarantee that at this momonet u would survive but of u live ur life responsibly, wisely and careful then u are much likely to survive for a long time. Instead of stupidly worrying about death that is not in your hands get involved in your life that u are fully responsible for. During bedtime when u fear death try to remember all the good things that u did during the day that made ur present happy and memorable.