How can I repair this door and deadlock?
Aside from replacing the door, you can purchase and install reinforcement kits for your door and jamb.

EDIT: These are also known as door wrap around plates.

 

As you can see, it contains a metal bracket that fits around the door. Some just protect the edge while other models extends a few more inches over the door and covers the holes for the dead bolt and handle.

Look around at your local home improvement store or call a local lock smith.

Get a new high security dead bolt while you are at it.