Require help, Website disappeared

Hello,

I have a problem with my website: https://regentechinc.com/ and am in need of assistance.

I should first mention that I was not the one who made this website, an acquaintance of an acquaintance helped set up the site and then gave me the log in credentials. Unfortunately I cannot get in contact with this person and I do not know anything about making a website or coding so please bear with me.

In case you need to know, the logins that I was given include ones for GoDaddy, WordPress, and cPanel/FTP.

As for the problem: all the content on the site has disappeared and only shows a sample page with things such as Hello world, this is your first post, etc. I am unsure when exactly this change happened but the sample post is dated Feb 22,2020 so perhaps then?

In an attempt at fixing the website, I tried to log in through the login URL that was given to me (regentechinc.com/regenlogin) but this URL no longer exist. The only login page that I can find is https://regentechinc.com/wp-login.php but when I try to log in using the credentials that were given to me, it says username does not exist. However, under web applications in cPanel, it shows the same login username as the administrator username for the website. I’m not really sure why I cannot log in and without being able to log in, I don’t know how to fix the website.

I am not sure what I should do from here so any assistance is greatly appreciated.

If there is any additional information required, please let me know.

Thank you in advance

The page I need help with: [log in to see the link]