how to get google serp ranking back

[terryward]

Review the guidelines of Google, if you have done anything that violated the guidelines then address the problem by removing bad backlinks, spammy links and double your effort in high quality SEO, content marketing and social media marketing.

Also check your on-page optimization, review canonicalization or 301 redirects, robot.txt files and make sure your website are being crawled and indexed by Google.