Unless your wort was over 140 degrees you most likely only killed off some of the cells. Yeast actually thrive in temperatures a little over 100. Your beer won't like it but the yeast will
BTW, fermentation can take up to 72 hours to start. Did you make a starter? Did you aerate the wort well? These things also contribute to the tart of fermentation. If you have not seen activity after 72 hours then you re-pitch.