.htaccess missing? Maybe. Will a dupe causes issues?

I had an .htaccess file. I cannot find it. I ran a search through the directories – nothing came up. I do use Pretty Permalinks, always.

In my WP years I have never had to add an .htaccess file manually.
I have questions:

1). Can or how does .htaccess disappear?

If I create an .htaccess file using https://codex.wordpress.org/htaccess :

2). If there is an .htaccess file that I missed, will adding another cause any issues?

3).I’ve only ever seen one .htaccess fIle for each WP install in my years of MultiSite installs. This https://codex.wordpress.org/htaccess is listing multiple places for .htaccess.
I am confused:
– where to place it or them
– how many do I need?

I’m not tech savvy, but I can follow clear and specific instructions for dummies.

Thank you