brand new user here. Actually my son, but trying to help him. We got a used pi 3 B off Ebay. it came installed with retro pi. My son didn't want that so from the dropdown menu he clicked uninstall. Now all we see is a very long boot up string but never comes to a home screen. I'm thinking he uninstalled or deleted more than he should have. Do we have to start from scratch and make a new sd card? Would it be easier just to buy a new sd card with the latest os on it?
It is booting normally to the command line. If you don't need to keep anything on the card I would write a fresh Raspbian Desktop image to the card using Etcher. See http://raspberrypi.org/documentation/installation/installing-images