Please use proper punctuation, capitalization and spelling when posting. It was hard to read your post because everything runs together. I am telling you this because you are new here.
About your problem. Use some of the grids your trying to sell and make him an indoor cage. Do you have more than this one boar? He may be lonely and that is why he is depressed. I am glad you brought him in from the cold as he could get sick or die if left exposed to the cold and/or harsh elements. If he is the only pig you have, you may want to consider getting him a younger same sex buddy or a spayed female for companionship. Pigs are very social animals and do much better with a buddy. Check out any local shelters/rescues in your area.
The problem with housing him in a box is that the cardboard will get wet and nasty after a few days and will have to be replaced. And he is stuck down inside with no way to see out. Pigs also love to see and interact with their surroundings.