Q: Hep me set up ethernet & wifi

Sounds like you went into area of settings too far... and made it harder to explain

what would not need to have been changed or re-set. To begin from the basics

and not know what experience you may or may not have, could take a book.

•Solutions for connecting to the Internet, setting up a small network, and troubleshooting - Apple Support

There are several aspects in the above page that may be helpful in re-setting up

of any number of kinds of networks. The basic Ethernet network setup is covered

in one of the blue-links in the above page; they go to other support page topics.

You would also need to become familiar with setting up Locations, then you may

not lose everything by going into other areas; or if you frequent several places that

offer a reasonably secure wireless internet access. Then you'd simply choose from

your saved Locations in your computer's internet networking preferences.

Most of the basics and some advanced topics are covered in the above page & the

associated sub-links within that page.

In any event...

Good luck & happy computing!