Re-named Files Now Comp Wont Work: UxTheme.dll Cannot Be Found

I wanted to install a new theme onto my computer the other day,rather than use Glazz or whatever it's called i found instructions on how to edit some files within the System32 folder on the C drive.It told me to re-name the UxTheme.dll and two other files that i cant remember (ibelieve they were called something like svchost.dll and hmui.dll,total guesses)First i had to take ownership of all 3 files,then i had to change the permissions to full permision on all three to full control,and then i had to re-name all the files rom.dll to.old and then the part that i think i screwed up was that it said to copy something and i missed that,so i re-started the computer and then the problems arose.It will come up to the login screen,then i log in,it comes up with a message that UxTheme.dll cannot be found, i click ok and then two screenes come up saying that the Windows Explorer and Desktop Manager are not working and windows cannot find a solution.It then finishes loging in and brings to to a black screen where only the mouse pointer is visible, and that's it.If i ctrl-alt-delete it brings up the screene showing me my options,logout,switch users, task manager,etc.I can log out,switch etc,but if i click task manager it also brings up a window saying the task manageris not working.