Sometimes dogs can become skiddish for a lot of reasons. The main thing is to get him back to being around you guys. Make sure that he is fed often. Try using treats to get him to come to you so you can pet him. Make sure that you do not express anger towards him. Watch and see if anyone including neighbors have been treating him wrongly.
If he used to be a loving dog, then most likely something someone did spooked him. You just need to show him love again. Doing things that dogs love, and showing him that your fine.
Going for walks, treats, play time.