my system preferences wont open. why?

Hi Cody, not much to go on, but try this...

Safe Boot , (holding Shift key down at bootup), use Disk Utility from there to Repair Permissions, test if things work OK in Safe Mode.

Then move these files to the Desktop for now...

/Users/YourUserName/Library/Preferences/com.apple.finder.plist

/Users/YourUserName/Library/Preferences/com.apple.systempreferences.plist

/Users/YourUserName/Library/Preferences/com.apple.desktop.plist

/Users/YourUserName/Library/Preferences/com.apple.recentitems.plist

Reboot & test.

PS. Safe boot may stay on the gray radian for a long time, let it go, it's trying to repair the Hard Drive.