What works for explosive speed/power is power cleans.
They are the best weights exercise for speed.
Other than that, squats, short sprints:10 metres(you can use weights here too, backpack) 20 metres, 30 and 40-45 metres.
Make sure you warm up and stretch before every weights session and stretch soon after(5 mins max)
Eat enough protein to rebuild the broken down muscle and build new tissue.
I would also use creatine monohydrate as it increases ATP(adenosine triphosephate) levels which are taxed very hard during sprints and power events.
It will also increase strength and power(strength and speed = power!)
Good luck mate