Key change problems :/

My key was unfortunately stolen (why dont they just generate???) and the way they stole it I cant change it now with darkys key changer/checker because and error comes up (failed to read hex key from registry error code:0 the operation completed successfully) because there was no key to be found then it closed it's self and in order to change my key I need the key checker function but I can't use it because darkys keychanger/checker forces itself to close. so does anyone have a alternate way to check keys? and also once i have one thats ok can I just change it via the registry?

EDIT:tryed changeing the key in regedit to a random one and opened darkys key changer again same thing happened
EDIT:SOLVED used CCleaner then as said below verified the cache

"regedit" you are on the right way! google that -_- and your done