Why my website dropped several pages to no ranking after wordpress theme update?

Hi,

I have a wordpress site for bussiness startup, and last week i've changed my wordpress theme with a new one. Now, the rankings dropped, my top keyword was position 15, now it's on 27, and several keywords went at least two pages down or from position 40 from no ranking. Why this happenned and what can i do to get my ranking back, or even better?

If you need extra details feel free to ask, didn't know what more i should post here, Thanks!

It might just be google recalibrating your site after a big change on your website. But it might also be the theme changed meta tags, headings, ... so it's less SEO friendly. You might've also just been in a google dance if it's a new website.