My charger isn’t working what do I do

I would try another cable

test it with another ios device

try cleaning out the iphone connector of lint and dirt

in that troubleshooting session, I would get a clue if the issue is with your charger, cable or the iphones connector

My Mac book is only 8 months old...and my charger stopped working today. I tried with my daughter's charger and it did work.

Does my have guarantee?

Yes so long as there is not accidental or user damage.