How to undo changes made to a .htaccess file - php

Question

I am fiddling around building my own CMS and playing around with the .htaccess file.
I was looking around the web for a snippet of code which would add a trailing slash onto every HTTP request.
When I inserted the code I realised that it would also remove the name of the subdirectory in which I was working.
URLS:
So this is what I had: localhost/project/index.php
This is what I wanted: localhost/projects/index.php/
This is the result I got: localhost/index.php/
But the real problem is this:
I saw the outcome, and I wanted to revert to example 1 from example 3. But after I deleted the code in the .htaccess file, the changes remained, and I have no idea how to revert this.
How do I revert this rewrite rule?
This is my .htaccess before implementing the "trailing slash"
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /tesla0.2/
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME}/index.html !-f
RewriteCond %{REQUEST_FILENAME}/index.php !-f
RewriteRule . index.php [L]
</IfModule>
This is my .htaccess after:
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /tesla0.2/
RewriteCond %{REQUEST_URI} !\.(php|html?|jpg|gif)$
RewriteRule ^(.*)([^/])$ http://%{HTTP_HOST}/$1$2/ [L,R=301]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME}/index.html !-f
RewriteCond %{REQUEST_FILENAME}/index.php !-f
RewriteRule . index.php [L]
</IfModule>

Answer 1

I assume that youre htaccess file is in the "projects" directory?
Try changing your rule to:
RewriteCond %{REQUEST_URI} !\.(php|html?|jpg|gif)$
RewriteRule ^(.*)([^/])$ http://%{HTTP_HOST}%{REQUEST_URI}/ [L,R=301]
You'll also need to clear your browser's cache, since the redirect is 301 (permanent), the browser will cache the redirect and use it indefinitely, since it's a permanent redirect.