Try not to die, given that nobody is producing food, electricity, natural gas, clean water, and the like. You'd have to figure out how to be able to feed and shelter yourself while being able to identify potential food sources, as well as ones that are harmful, the behaviours of animals you are both trying to hunt as well as avoid being hunted by, learn how to start a fire without convenient tools like matches or lighters, and so on. It would be a depression, brutal existence that would not get any easier unless you were able to adapt and you were able to find something to fill the void of the lack of human companionship, something that we as a species have depended on since the very beginning.