My son in law just had a shut down with ptsd and i don't no how to handle it or help him?

Of course: Even professionals can see this as difficult. You need real help! What you might be able to do is insure safety. Clear away major weapons and car keys. Try to get calm support of a trusted other - in person or on phone or social media. Offer water, comfort food, least upsetting music. Try to shut out irritating stimuli - advise Dr/ER/police of situation as appropriate.