Urgent Error on Wordpress Website

Description

Hello,
Thank you in advance for your time.
PLEASE NOT: we are only looking for UK Based developers for this project.
Our Wordpress site is currently hosted on one of IONOS dedicated servers. We received the following message yesterday after the site was displaying a critical error:
"A few minutes ago, our antivirus scanner detected that a malicious file was uploaded to your webspace.
The file can be found in your webspace at the following location:
~/benchmarkscaffolding.com/wp-includes/capabilities.php"
The capabilities.php file was replaced, and the site displayed as normal. After a few minutes, the site then goes blank (its current state), and no errors display on the front end, and there is no access to the back end.
We are looking for a developer that can look into this, and have it resolved within the next few days.