Returns traffic

How do I restore traffic lost due to a new algorithm update from Google?
And I lost traffic after I changed the theme in my blog and changed it to valid amp.

From my experience you can make a subdomain like www1.yoursite.com or w1.yoursite.com and just notify google via google search console about this address change. You should also do a redirect via .htaccess to your new domain.
I had the same problem on january update. My website was on the first page for my main keyword and suddenly dropped to page 6-7. I did this subdomain change and after 2 days my website was back at fist page just like magic .
Hope this answers your question and good luck .

Domenikogj said:

You should also do a redirect via .htaccess to your new domain

Click to expand...

He didn't mention a new domain, did he?

Aty said:

He didn't mention a new domain, did he?

Click to expand...

He asked HOW didn't he?
I gave my advice based on my experience. It's a subdomain of the current domain, but acting as a new domain. It's better than changing the whole domain in my opinion,because you get to keep the link juice.