Changed shortname and home directory name and don't know how to set it back

Question

so i changed my short name and home directory name because i bought the macbook used and i was trying to rename it to my name.
Like all the others now the desktops back to default without any of my files/music, i know its still here its in the old account folder how do i just reverse this so i can have my desktop and everything back.
heres what it is like:
my users folder there is a home icon called "Josh" which is my name, then there is a folder icon called "nick" which is the old name and it contains all my files etc. then a shared folder icon.
what do i do?
p.s. i tried the method of adding "_new" onto the home icon called Josh and it said i couldn't change it because its part of Mac OS X or something...

Answer 1

if you bought a used computer the first thing you should do is reformat the hard drive and reinstall the OS. anything else is less than prudent. it will also let you name your computer and your user as you like.