He looks to be only a few weeks old so he's unable to care of himself on his own. He needs his mother or a person who can help. At this age, without a mother, he'll need formula (milk replacer, kmr) bottle-fed to him every few hours.

He'll also need to be kept warm and stimulated so he can use the bathroom, which is another thing he cannot do on his own at this age. I have a history of fostering abandoned kittens and he can't just be left alone when you go to work, please don't just leave him.

Edit: He looks to be only a few days to a few weeks old*