Does it start with the old key, or you do not have it with you? Was the new key coded?
Does it have a 'green key' displaying on the dash when cranking? If you insert the key and turn it to Accessory 2, the 'green key' should blink and then go away. That is the immobilizer system
Do you hear the fuel pump prime when you put the key in ACC 2?
If the key comes out, then you know it is your ignition lock that is at fault, and expect to pay a pretty penny. Lot of vehicles have to have the whole ignition key module changed, as opposed to just the cylinder (cheaper route).