Only an x-ray will tell if it is a fracture or not. Probably fracture.
For sure, avoid fast movement while it's mending. Slow movement's fine and indeed, flexing slowly is desireable (should help boost healing circulation).
Glad to hear it's much better today, sounds like it's well on the road to recovery. I anticipate you can return to wall punching after three or four months (but know that repeated injuries are more apt to become arthritic -- trust me, you don't want that sort of 24/7 pain).
Thxs for information it's much better today as I can straighten it but the kuncle has sunk in a little bit and a bit pain when straighten and if I clinch my fist and let go fast to a normal hand it hurts so do I still have to worry?
Covering the knuckle bones is a layer of cartilage, a very hard tissue (though not as hard as bone) which has some resilience and flexibility but not much.
If you cannot straighten your hand, the injury has likely led to swelling and is starting to freeze the joint's flexibility -- I urge: keep a cold compress on it, perhaps keep it well elevated, too. Both steps are to reduce blood pressure worsening congestion, reducing that ought to help assist healing.
A local sports' specialist dealing in boxing injuries may be of better assistance. You might do well to consult a doctor (but I suspect there's not a lot that can be done, other than an x-ray to check to see if you've actually broken a bone).
I can barely straighten my hand now and it hurts quite a bit and what's the cartilage?
You may have broken the cartilage, so I suggest you see a doctor sometime over the coming week or two. If it aches, cold packs ought to help. I urge refraining from punching more walls until after it has healed.