Hard to say without seeing it. What do the lines look like? Horizontal or vertical? What happens if you try to reset it again?
is the charning light on when you plug it it?
If you have a lot of deep black horizontal lines that don't seem to change at all when you restart then,
he screen is broken needs to be replaced. In that case try amazon first, they may send you a free replacement. If you're out of warranty and Amazon doesn't help you can send it to a third party. Just google "kindle repair" and you will find places. Alternatively, you can try replacing it yourself
http://www.portatronics.com/guide has step by step instructions.