Need Serious Dog Training Help!?

I have a one-year-old female cockapoo who is spayed.
For a while, now she just simply won’t let my sister or I pick her up. Whenever Mandy (my cockapoo) even has the slightest feeling that my sister or I want to pick her up, she immediately growls. Then, if you try to physically move her, she’ll go crazy like an ill dog and sometimes even bite.
I’ve already tried picking her up and shouting, “no,” whenever she growls, but it didn’t work. I then tried to reward her with treats every time she didn’t growl/bite, but that didn’t work because – you guessed it – I can’t even pick her up. Ever.