First of all: don't panic! Be methodical. If it is a theft or a burglary, call the police immediately, who will come to your home. If it is another incident (water damage, flooding, fire, electrical damage): take photos, measure the extent of the damage, describe the damage, add the purchase invoices for the damaged objects, and send this file to your insurance company. They may offer you a refund if this type of damage is covered by your policy.