4/20 problem!!! Light died!

i have 7 plants under 1 400w MH and 2 100w hps lamps.. last night the 400w mh died overnight but the other lights were fine. the plants are about 8 inches tall and have 3 to 4 sets of leaves. whats should i do ???!! HELP

get some flouro to light them up or put them in the sun untill you get new light