I have a slightly crooked finger joint due to an accident a few years back. Will wearing a splint fix it?

No. At this stage of the game i doubt any splinting will help and a consult with a hand doc could offer you some treatment options if you were looking to fix the problem.
Not likely. The distortion you see in your finger is likely permanent.The finger & its supportive ligaments/joints have accepted the new normal as the finger you have.A splint might have helped if applied @ or near the time of the injury. An evaluation by a hand specialist or orthopedist might give you an idea if surgery/controlled refracture/pinning might help.