Many simple functions just don't work

Hi folks,

would be nice if somebody have an idea why certain things are not working in my codeIgniter version 3.1.11. I tried already everything. 

I even tried it with copy and paste of the official tutorial.

My guess is that it has to do with the index.php as route:
- What is not working at all are selection of single data from the database via slugs while selection of all data works, yet the link to the general data will be with localhost/my_project/index.php/view while it automatically skips the index.php by a slug selection and then cant find the page.

- The same problem comes up by data entries 

- Also I tried to remove the index.php issue with .htaccess file but all versions in the web which might work doesn't work

- Furthermore, colors and so on from bootstrap themes works but not the containers and navbars etc.

I am really desperate meanwhile if I have to give up on codeIgniter or if there would be a simple solution or reason somehow.

I use a xampp localserver with PHP version 7.4.5 and have the codeigniter version 3.1.11

@Phillip10,

What are you using as your configuration for your web setup? WAMP? XAMPP?

I use XAMPP v3.2.4 with PDI(s) 13068 and 4144 and Port 80, 443 for Apache and PID 20556 and Port 3306 for MySQL.

And I have to admit I am new in this things, but when I make it without framework, just with file structure the things work and I just tried also the 1 to 1 approach of examples from tutorials where it worked but by me it don't. I checked in the web and could see that a lot of people faced similar problems, but all suggested solutions doesn't work by me. So I thought maybe it has to be with the environment. And need here a way out.

@Phillip10,

I'm going to try to help by addressing one issue at a time. My next question. Is the mod_rewrite module for Apache turned on?

Thanks. Yes it is on. I checked it.

@Phillip10,

Is the content of your .httaccess file untouched or did you customize it?

Also, here are some useful video links that may be helpful.
https://www.youtube.com/watch?v=7aoTeReWLMc
https://www.youtube.com/watch?v=I752ofYu7ag