If your site’s traffic suddenly dropped, it’s possible that Google penalised you.
What the Google Penguin Penalty is and how to fix it:
Start by going to https://majestic.com/.
2. Type in the URL of your website.
3. Go to the page’s bottom to view the anchor text percentages for your site.
Anchor text that includes variations on a targeted keyword, brand name keywords, naked URLs, and other variations that occur naturally are all good to go, according to 4.1.
If you’ve only got exact match keywords, you’ve probably been hit by Penguin (see section 4.2). All of your unnatural backlinks should be disavowed using this Google tool: https://www.google.com/webmasters/tools/disavow-links-main.
The Panda Penalty and How to Overcome It from Google
1. Visit https://www.google.com/webmasters/tools/home.
Step 2: Navigate to your site (or “add a property” if you haven’t already)
To make HTML enhancements, go to “Search Appearance” > “HTML Improvements”
Fourth, if there are problems noted, address them all.
SOURCE: https://www.robbierichards.com/seo/identify-recover-google-penalty/