Help! I took my negatives to a photolab for recopies and they lost the pictures and negatives. What can I do about it? What are my rights? And where can I get help?

I don't know your rights exactly but I wouldn't give up hope of finding them. Someone else probably received them by mistake. And the people that received your negatives and prints are probably sitting at the processor. I would put some kind of pressure on them. Ask them to see which prints haven't been picked up and have them call those customers. Kind of hang around and become a nuisance but not too much so until they find your negatives.

Most labs will just reimburse you for your lost film and not much more, and they post a policy to this effect.

A good professional lab that wants to protect its reputation might go out of the way to make nice when they've made a mistake and offer other forms of compensation, like additional free processing (Modernage in New York did this once for me).

If this was a professional job with a lot more at stake (fees, models, assistants, studio rental, travel, etc.), then you may be able to pursue more substantial compensation through legal means, on the grounds that the law may offer more protection than the lab's policy suggests.