In the US, the broken into car (windshield or windscreen damage) would normally be covered by comprehensive insurance though the personal belongings stolen from a vehicle are usually not covered by auto insurance but instead by a person's homeowners or renters insurance.

In the UK, it appears that comprehensive (fully comp) motor insurance policies allow for claims due to loss or damage to personal effects in a car, up to a stated limit, after an excess fee (deductible) is paid.

If you do not have fully comp then if you had a stand alone personal belongings or contents policy this would cover your personal items that were stolen. Contents policy typically seems to be for household items but some do covers autos.

Personal belongs or personal possessions polices typically extend to cover accidental damage to or loss of items which you take out of your home, so again you will need to check and see if your coverage extends to a motor vehicle if you have this type of insurance.

If you are from a different area of the world then you would need to speak to your agent to find out how to make a claim for your windscreen damage and also find out if your personal items and stereo are covered by your motor cover or another coverage such as a personal effects or burglary.

Without knowing the specifics of your insurance policies we cannot tell you which coverages would cover this theft situation however your agent that knows the particulars of your policy and coverages can advise you how to make claims for your car being broken into and your stereo and other personal items being taken.

In the US get a quote for car insurance here with us.