See if you can provide pictures or drawings of the boat, tell us what sails
he has, too. Strategies for sailing upwind and downwind are different as to sail plan and how you set things up. What kind of a boat is it? How is it rigged? Can also suggest he heave to for a few hours (one sleep) just to get enough rest to be in a little stronger position after you've had time to secure him some simple suggestions.
Simplest: dead down wind
with two headsails up, main down. Sheet from each clew through a block to the tiller. Helps if the two sails are the same size.
On the wind
. balance the tiller close hauled. Tie it there. Sleep till you wake up.
He probably wants to stay on course, but if he can get the boat moving in a reliable direction, then he can rest, and once rested will be in a better position to understand the instructions people from here will come up with.
We wish him well.