Getting Fatal error repeatedly

I am getting this fatal error when today i want to edit my website. I do not know what i updated or what i did yesterday so i am getting this error. I tried everything disable plugins through hosting panel. tried to update my root files like .htaccess, wp-config.php and wp-load.php. I took backup through my hosting. After backup website start working but when i again try to login into wordpress dashboard it gives the same error again and again. Please help me so i can remove this error and able to use my wordpress dashboard.

Fatal error: Uncaught Error: Call to undefined function wp() in /home/u526093132/domains/contesasia.com/public_html/wp-blog-header.php:16 Stack trace: #0 /home/u526093132/domains/contesasia.com/public_html/index.php(17): require() #1 {main} thrown in /home/u526093132/domains/contesasia.com/public_html/wp-blog-header.php on line 16

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