Theme not found in themes folder

I have uploaded a theme through WordPress and the theme was successfully installed. but when I go to my cpanel to change the CSS the theme is not on the themes directory.

I have tried changing the CSS thorough wp but no luck the CSS is not changing.

It has to be there. Not trying to be a wise-guy, but it has to be there.

Instead of using your control panel, download and install free FileZilla.
That will be using an FTP account you can set up with your control panel.
Much easier to work with ... files back and forth between PC and website,
and editing those files.

make sure you're looking at the correct spot for that theme directory.