It can still be fixed if she is 12 weeks. When ever she bites you. say "Ouch" in a high piched loud voice. (it mimicks the sound littermates make when playing gets too rough)If she gets shocked enough to drop the item then take it away and call her to you to play. If she doesn't... show her a treat that she likes and call her to another room. If she comes praise her and give her the treat. then carry her over to the item and say "No". Then put it away.
If all this fails.... see if you can get some advice from a trainer. Petsmart has good ones in my area, but I know they are not all good. The Petco in my area has crazy trainers...I can't believe it sometimes. Also, The Humane Society might have a behavior counselor...they usually give free advice. I'm so sorry. I know how that feels. My old dog was like that too.
How old was she when you got her?