A weird MouseLook bug

I was working on a game in unity and something didn’t work like it was in the tutorial I followed. In the tutorial Unity Particle Pack was used so I desided to install it aswell.
When I tryed to install it I got a warning popup:

To be save I tryed it in an empty project like the picture says. In the empty project I couldn’t see any diffrents and nothing that could be bad for my main project.
So I installed the Particle Pack in my main project aswell. As it was done I soon noticed that my player couldn’t move as before. In thought that if I just restart the project the problem will be solved (because I hadn’t saved after installing the package). As I was back in the project I checked if the problem is solved. But it wasn’t.
Every time I tried to rotate my player around it didn’t turn the player like it normaly should. It turned him in a weird way. But the center it turned around was not the player…
I have tryed to make a new player in a empty scene but the same problem came up again.

This is what my problem looks like:

View from the Scene TAB:

I haven’t changed anything in my project or scripts that could possibly cause this bug. It has to be coming from the package I installed and the project settings it changed.
I don’t think you’ll need my scripts but if you do I can send them for better help.

Please if anybody knows what the problem is and how I can fix it please help me. I don’t want my project to be unsavable.

I have finaly done it! I just extracted the files into a new project folder.