If there were a worldwide communication blackout for one day what is the worst that could happen?

I have worked with many companies and I will tell you that the amount the internet is relied on in so many business is very surprising. 1 day is probably ok and will just hurt profits but in a few days much of the world will simply shut down and you will not be able to get food or gasoline or power.

I could be stuck in an elevator.  The one that was taking me to the 2nd floor restroom.  :  (