Q: i want to restore my computer so its like i just bought it

1. Insert the install disc that the computer brought and press C key in boot

2. Open Utilities > Disk Utility, select the drive and erase the disk

3. Install. When it ends, open  > Software Update and update Mac OS X to the most recent version. Also, insert the Application DVD to use iMovie, iPhoto, GarageBand, iWeb and iDVD

Have a look here...

http://www.ehow.com/how_5926047_restore-macbook-factory-setting.html

if your macbook came with snow leopard - click HERE.

if your macbook came with Lion - turn your Macbook on while pressing the command + r keys and release the keys when you see the apple logo - when you see the disk utility menu, erase your drive then reinstall your OS.

more than likely - you have to follow the first one I suggested - Snow Leopard...

good luck - hope you get it sorted out..