i am 6 grade and long ago i dropped my phone in a cup of water. it did not work for a long time so i put it away for like months. well i wanted to use it again so i got it and put it in the frezzer...
Your phone might need charging, or it is broken. If you open the back of you phone, you might find a battery inside, that might need to be changed.
Hardware failure. Check with your carrier about a warranty replacement.
Turn it off then turn it back on