IPhone 4s Screen Black

I had my iPhone in my pocket and then I took it out too look at the screen and then it was black but the battery was at almost 80%. Its been on the charger for the last hour now and won't do anything. The Lock button also on my phone is broken.

Hold down the power button on the top right and the circle button at the bottom at the same time until it turns off. Then turn it back on.

There. You are fixed.