Does the prayer and ablution of the worshiper become void if the splint falls off his hand during prayer after wiping over it during ablution, knowing that his hand has not yet healed?

The falling off of a splint during prayer invalidates it. As for ablution, it is not invalidated by its falling off if it is put back and wiped over immediately. However, if there is a long interval, the ablution is invalidated according to those who hold that continuity (muwalat) is obligatory.