HOW can I help My Father feel better?! (please help me, I need all the advice I can get before it's too late)?

My father has been through hell and back again. My Mother needs to learn patience and needs to be nice. BUT...besides that...WHAT CAN I DO FOR HIM?! He's got a cold and came up to his room. He slammed the door and HIT THE WALL!! He hit it hard 3 times. We share a wall (im right next door in my room) and my whole wall shook and I thought I was gunna see his fist go through it). IM SO SCARED and IM SHAKING LIKE A LEAF. He's been depressed, hates this house (we don't own it and live with gma and pay rent), he hates his job now, and he seems miserable. He's got heart problems and is tired of doctors and stuff. I WANT HIM HAPPY. IM SCARED. PLEASE HELP ME!!! What can I do for him or say to him to make him happier?