Do you have spark? Were the plugs actually WET with fuel when you took them out (i.e. was it flooded, or were they black/brown from wear)?
You can check spark with a pair of insulated pliers and a friend.
Pull one of the leading plugs out of the engine (the ones on the bottom). Put it in the spark plug wire. Hold on to the RUBBER boot of the wire (get away from the plug as much as you can) with a pair of rubber handled pliers (insulated is preferable) NOT WITH YOUR HAND. Put this in close proximity to the engine block (1/4" away, you don't want to touch it, but you want spark to jump across), and have someone crank over the car. DO NOT TOUCH THE PLUG. IT WILL HURT.
If you see a yellowish spark, it is weak. If it is blue/white, it is strong. Start with this test to diagnose.
If you have bad spark, it could be the following:
Coils
Wires
Battery
If you have spark, then it is a fuel issue.
Could be:
Injectors
Fuel pump