Try FN and F4, that should wake it up.
It sounds as if your settings are wrong - try pressing FN and the brightness button to make the screen brighter.
If you believe the laptop is faulty, you should take it back to where you bought it from.
Do not be fobbed off - your contract is with PC World and nobody else. As it is still very new, you are entitled to a replacement or a refund.
The DVD - are you sure you are using the right type of disks? They come in different formats.