What should i do?

Not being cute, because you're obviously worried, but I can tell you as a kid who was in that position that to this day I still have horrible memories of the "friends" I was forced to put up with. I still hate them, decades later. Seriously, I resented it at the time, too. I still do. If the kid lacks confidence, there's a real risk of making it worse. If this is an intelligent kid, trying to put anything over on him/her won't work for long. If you want the kid to have friends, I suggest some tactful, "accidental" meetings with kids, no emphasis at all on what "should" be happening. Sooner or later, it's likely that someone acceptable will show up. Anyway, the kid may have a point. Maybe the other kids are jerks. May not be much of a social life, but it's better than having one the kid hates. Another factor is that your role could become distrusted, if you become seen to be the source of these unwanted intrusions. Suggest play it cool, and be patient,

You don't say how old your child is, but if he's under four years, you could start by taking him to a Parent Toddler Group, if you have such things where you are. This encourages the child to mix with other children, whilst the mothers can get to know each other. Sometimes this comes in especially helpful because the children are very likely to attend the same school and you will meet the other mothers every day. Then, from there, gradually ease him into kindergarten, because if he can't socialise by the time he goes to school, he's going to have some tough times with the other kids there. If he's older, then maybe take him along to some youth activity, or train him with a sports team, such as football, softball, baseball... take him swimming, to soft play areas where you can't actually enter in the soft play and he is likely to make a friend or two. There are lots of possibilities if you have the time and the willpower. Good luck with this... I feel sorry for him that he feels he can't join in with the others. He's missing out on so very much as far as growing up goes.

I think a lot depends on your child's age. Sometimes it's just a phase that they are going through. Some kids feel more like loners naturally. But sometimes it's just a time in their life that they are not interested in having friends. If he withdraws from his family as well, I would be worried. But if he still interacts with family the way he always has then maybe he just enjoys his alone time. I guess if we knew more about his behaviors and etc, it would be easier to give you suggestions.