Acer 3100 screen wont turn on.

Question

i have an Acer 3100 Aspire laptop. about a week ago i powerd down the system and closed it up. placed it on my desk for the night. the next day went to turn it on, and the rest of the computer was working fine, although the screen was still black. like no power was getting to it. it had just had windows XP SP3 reinstalled on it, maybe 3 weeks before and has been shutdown every once and a while. i don't know what would cause this problem?