The Venus Flytrap is a lying / hanging plant. When a trap of the Venus Flytrap turns black, it goes through a very normal process. The main reason the trap turns black and dies is that the trap is at the end of its life. Each individual trap of the plant has about a three-month life span in which it catches 1 to 4 insects. The leaves die at the same time as the trap and new ones grow back. You can simply remove the dead leaves so that more power can go to the green leaves.
Tip: it is wise to touch the beaks as little as possible and do not feed the plant insects.