Use these techniques to search for hidden social profiles:
Search by Email on social media networks such as Pinterest, Facebook, and Twitter;
Search by Username – many people repeat usernames from one platform to another;
Google Search – use someone's full name between quotation marks as in "John Doe" followed by their city "New York" and add a command to find within the website URL. For instance: "John Doe" "New York" site:facebook.com;
Google Search by Image - go to images.google.com and search the person's name or other nicknames they frequently use. If their Twitter or Facebook profile photo shows up, click on it, then select "View Page" and you'll land right on their respective social media page;
Use other web search engines like Yahoo, DuckDuckGo, or Bing. For more in-depth searching, try the meta search engine DogPile, Monster Crawler, and WebCrawler (the oldest surviving search engine);
Use Wayback Machine - World Wide Web's digital archive created by the nonprofit organization Internet Archive based in San Francisco where you can see web pages that no longer exist.