whirlpool duet washer won't lock

I have a Whirlpool Duet Washing Marchine about 10 years old.

The washer stopped mid-cycle b/c it was unbalanced. Instead of running a spin cycle my Son pulled on the handle until it opened. :mad:

Now the washing machine door will not lock. The door handle (which I have replaced at least 3 times for probably similar reasons does not appear to be broken (8181877 is the item number for that part)

So it is probably a latch inside the machine?

Tell me what part I need and if my husband can attempt this repair himself.