Updated XAMPP now it won't work!

[rob33]

I had a previous version of XAMPP which worked ok for what I needed. Recently I tried to run a new Wsite on it and it told me ( what I suspected) It does not support latest versions of WP.

To that end I installed v3.3.0 I copied site files to htdocs for one testing site, then tried to run it, I also followed some instructions to try a test.php.
Neither options work on localhost.
I have obviously missed something, but since the last time I configured this was in 2016, I am not surprised things have changed.
I had hoped to be able to copy all my site files to htdocs and have the new version running. Not the case!

Does anyone have any GOOD instructions for forgetful me?

http:// localhost / phpmyadmin DOES work, but not sites.

[Nobbie]

You probably overlooked all SQL Databases, which arent stored in htdocs folder.

[rob33]

It was a couple of issues, one, the length of time since me originally installing ( and forgetting stuff) and two When I first ran XAMPP, I copied all files and SQL DBs FROM the external hosted dev area, TO my local machine.
Obviously they worked fine.

The problem I have now, is I copied site files from the OLD install htdocs, then imported the SQL DB via PHPMYADMIN, the test.php file worked,

I cannot get a more recent copy of a site working despite copying files and DB. The need to update XAMPP was because my version won't support latest WP. (NOW ON v3.3.0)
I am now getting "Error establishing database connection" The DB NAME matches in wp config, I am unsure what else to check.
PLUS
Now that I'm actually wanting to create new WP sites from SCRATCH on XAMPP I am missing something.
Basic question Do I need to install WP as well as having updated XAMPP in order to create sites from scratch (Not needed to before.)
Sorry for basic questions, happy to read any info links anyone can post. When I first did this all worked well but I now need to write WP sites from scratch on my local machine.

[Froosh]

Short answer, you are likely going to find limited information on installing WP here. XAMPP supports running WP sites.

That said, installing WP under XAMPP is easy. You download the desired WP zip package, and extract to a folder under xampp/htdocs. Rename the folder to whatever is appropriate. Create an empty database using phpMyAdmin under XAMPP. Finally, with Apache and MySQL are running, navigate to the site where you placed the WP files. If, for instance, placed the extracted WP files in xampp/htdocs/mywp, this should be http://localhost/mywp. At this point the WP site install takes over. If you need more details, search the web, and I am sure you will find what you need.

[rob33]

UPDATE.
I answered the last part of my question.
I would like some tips on where to look to resolve the Error establishing a database connection.
Almost there...

[Nobbie]

A database connection requires the database name, a valid username (which is granted to fully access the database), a valid password, a valid host and finally the client must be allowed to access the SQL server. Did you check all of these credentials?

[rob33]

After much head scratching, this now resolved, thanks.