Do you mean by being uprooted to different places as a child? This happened to me but I put down new roots and made long-term friends as an adult. I'd think the advice for people lacking roots would be the same as for anyone who lacks friends and/or has lost connections? There are also people who lived in an area all their life but maybe friends moved away etc and they found themselves lonely. Seems to me an answer is get involved with things - volunteering, sports, arts, music etc, and for those religious faith, get involved with that, church or otherwise, as long as its a diverse inclusive tolerant supportive community.