If she is still fighting after a week...you still have a chance. Often pups die after a few days. I am assuming she was vaccinated? So she must have gotten some immunity?
What was her vaccine schedule? When did she get her first vaccination? If they are started too early....the vaccine cancels the immunity to the disease.
I agree with the others, get some Parvaid...I've heard nothing but good things about this stuff. Also go and buy some jars of baby food (different meat flavours) and see if you can get her to lick some food off of your finger...and get her appetite back again.
Fingers crossed that she will get better.
Gina