What is the most effective way to recover lost search engine traffic?

This has happened to me twice and the pain is so enormous. The first thing is to check Search Console to see which pages has drop in ranking, and to confirm which keywords has vanished. Then try to audit your content. Maybe it's low quality or maybe it was outdated. Update the old posts, add fresh info, build small backlinks as well. Those are the things needed to recover your lost ranks in search engines.