problem with site

Hi, I’m having some problems here, I logged into my site earlier after a wordfence alert email as follows

This email was sent from your website “Hypnotherapy Bolton Psychotherapy Service” by the Wordfence plugin.

Wordfence found the following new issues on “Hypnotherapy Bolton Psychotherapy Service”.

Alert generated at Wednesday 1st of February 2017 at 12:50:42 AM

Critical Problems:

* File contains suspected malware URL: /home1/talkinv4/public_html/wp-content/themes/enfold/config-templatebuilder/avia-template-builder/php/html-helper.class.php

Warnings:

* The Plugin “Yoast SEO” needs an upgrade (4.1 -> 4.2).

https://wordpress.org/plugins/wordpress-seo/changelog

I then deleted the file as it suggested and there was a 500 error

I contacted bluehost support and the conversation with them went as follows:

6:49:40 PM stuart cale I got an email from wordfence saying “This email was sent from your website “Hypnotherapy Bolton Psychotherapy Service” by the Wordfence plugin.

Wordfence found the following new issues on “Hypnotherapy Bolton Psychotherapy Service”.

Alert generated at Wednesday 1st of February 2017 at 12:50:42 AM

Critical Problems:

* File contains suspected malware URL: /home1/talkinv4/public_html/wp-content/themes/enfold/config-templatebuilder/avia-template-builder/php/html-helper.class.php
6:50:08 PM stuart cale so I went in and deleted the file as it suggested and now the site is not accessible
6:50:38 PM Shrimati P In order to assist you further, please provide the last 4 characters of the Main account password to authenticate you as the owner of the account.

6:52:15 PM stuart cale hello?
6:52:21 PM Shrimati P Yes, I’m here.
6:52:37 PM Shrimati P Your main password is expired. Please reset your password.
6:52:41 PM stuart cale is it a big problem?
6:53:05 PM stuart cale can you send a link to do that?
6:54:06 PM Shrimati P Sure. I have sent the reset password link. Please check your mail.
6:54:38 PM stuart cale ok will you leave the window open while i do it – I’ll have to go to my other computer
6:54:45 PM stuart cale will take me an hour or so
6:57:27 PM stuart cale
7:00:08 PM Shrimati P Thank you for validating. Can you please hold while I review your account?
7:00:32 PM stuart cale yes – i might be a bit slow replying but please don’t close the window on me
7:01:35 PM Shrimati P Okay sure.
7:02:03 PM stuart cale do you see the description of the problem i posted above?
7:03:13 PM Shrimati P Yes, I can see.
7:12:56 PM Shrimati P Still working on it. Please be on hold.
7:23:38 PM Shrimati P Still working on it. Please be on hold for few more minutes.
7:29:35 PM Shrimati P Can you please check your website
7:31:12 PM Shrimati P I have set the theme to default. I would suggest you to uninstall and try re-installing the theme and check if it works. Or you may need to contact your theme vendor regarding the theme issue.

I’m lost now, can you please help me?

Stuart