If it is a puzzle lock, the only way to get a replacement key is to have the code that came with the locks when new, then contact the manufacturer and request a replacement key.
Otherwise a replacement will be impossible to get.
The reason you can’t get a socket hammered on to work is because the nut is smooth, so there isn’t anything for the socket to bite into. You may find success using a dremel to cut some flats into the nut and then force a socket on to try and remove it.
If you are going to keep trying to work on your car yourself, you need to invest in some good quality tools, and I’m not talking Harbor Freight.
At this point you will be better off taking it to a shop where an experienced mechanic can get it done.