My Minecraft has a really bad delay.

My Minecraft has a really bad delay. I would press W (the forward button) and after 10 seconds it would go and wouldn't stop after a while. any key I press.. Mouse is fine but when crouching, running, walking, jumping, anything involving the keyboard it will not work. Please fix  I cant do anything! I would really love to play but this delay is making me so mad. Most of the time I would play a server game and I would walk right off the edge and die.. its not fun when playing with this bug.