If you find on collecting your baggage that it has been damaged, if possible, you should immediately report your damaged baggage to the Jet2.com (if flying with Jet2.com or Jet2holidays) or Swissport (all other airlines) representative in the baggage hall.
You should document the damage by taking clear photographs and keep a hold of your baggage tags and boarding passes.
You should then submit a formal claim to your airline as soon as possible, this can be done via most airline websites.