hey man that's just bad luck. but don't get too down about it. just buy a bag of weed and get some seeds. if there are none, ask a friend for one or two. all you got to do is start growing another one so that your granny doesn't feel upset for you. it's not the end of the world because your first plant died. a lot of people's first grows go bad. so don't let it get you down. just try again and again and again until you get it right. read through a lot of these posts. almost everything is addressed once or twice. good luck next time.