Wordpress theme hacking show japanese keyword in Google

Hello guys…
i am using envato 1 year plan for wordpress website . I am using envato 3 theme on live website. but these themes have problem. someone hacked these theme and change my sitemap, index.php file and robots.txt file. in my sitemap they add 20,000 link and my website name show in google in japanese language. May be theme have problem. only envato element provide theme show these problem. other site theme work properly. How can i solve these problem

I have the same problem

We had try many ways to get rid of this malware and seems to come back again