MYSQL missing

Hi All,
I have seen the 2 other posts regarding the topic of receiving the error message:

Your PHP installation appears to be missing the MySQL which is required for WordPress.

Unfortunately, they do not help us to troubleshoot the problem we’re having. What is baffling us is we set up a blog through the same hosting (registeradomainname.org) a couple of months ago with no problems. The new site we’re setting this up for is registered and hosted by this same company, and we’ve gone through all the same steps, but are getting the above message.

We don’t know what to do.

We’ve checked and doublechecked our username and password, and set it up just like the previous blog, but it is acting as though the database doesn’t exist.

Can someone please, kindly help us figure this out?
Thank You!