Help all.

I had sprinklers put in last year and the guy that put them in didn't
fully get to winterize the system. He said he only got 1/2 done as he
did it too late and things were already starting to freeze. He then
said don't worry if anything is damaged he would fix under warranty.

Now guess what, I can't get ahold of him. I think he is out of
business (I wonder why)

We live in Canada so yes things freeze pretty bad, I'm just wondering
what kind of damage I can expect and how would I fix it? Would each
head need to be replaced? How bad would the damage be?

The ground is still frozen up here so a few more weeks before I can
try it out. How will I be able to tell if there is damage and where
the damage is?