Problems regarding security made on my computer

Hi everyone, my name is jeff. I am having problems from the "security changes" i made on
my computer. I just started taking lesson on PC security the other day and tried to apply my knowledge on my PC but dont know how to undo changes i made.

I planned on restricting a certain on line game on our pc because i dont want that somebody using our pc. below are the procedures i made but not that exact.

<start> <run> i tpye gpedit.msc

this will bring me to GROUP POLICY
went to USER CONFIG
and somewhere on USER CONFIG i found out that you can restrict certain programs
i click enable then add "elementclient.exe" (this is the launcher of the game which i wanted to be restricted).

after this when i open programs on my pc it says "THIS OPERATION HAS BEEN CANCELLED DUE TO RESTRICTIONS IN EFFECT ON THIS COMPUTER. PLEASE CONTACT
YOUR SYSTEM ADMINISTRATOR.

this includes opening Iexplorer, Yahoo messenger and even if i try to open gpedit.msc or and dos programs that thing pop out. .

this really made sad that maybe im not good at software programming.

Please help guys..

btw im using windows xp if this might help.

i cant open 90% on programs on my computer. i was shock to see that explorer on this part runs.. here i will give a link. i went on OFFLINE WEB PAGES under WINDOWS