Best to go back to the beginning and put everything back in XAMPP to the defaults - where did you see to do all that moving of the php.ini etc?
not anywhere in XAMPP of that I am sure.
Now the only php.ini file to edit is in
.\xampp\apache\bin folder.
Uncomment only your known required extensions (not all of them) in that file only - save the php.ini file and restart Apache after editing.
http://localhost will go to a php Welcome Page with lots of demos to test your XAMPP installation.
Check out the
phpinfo() link for the current Configuration file being used by Apache's php.
If you add php code to a coded html file then you will have to rename the file with a .php not an .html extension so that Apache knows to parse the php code.
Double clicking on a php file in Windows Explorer is not the way to go for a php file - it has to be parsed by a server as it is a server side language.
Your php and html files go in the DocumentRoot folder which on a default installation is the
.\xampp\htdocs folder then the URI would be:
http://localhost/yourphpfile.php
You can separate them if you wish by placing them in a folder in the htdocs folder.
.\xampp\htdocs\yourfolder
then the URI would be:
http://localhost/yourfolder/yourphpfile.php (or yourhtmlfile.html no php code).
Get the idea?