I tried everything had nothing to lose but to replace carpet so I tried WD-40. I sprayed it on, let it sit for a few minutes, and pressed it out. It took a while and a few cans, but it was cheaper than replacing a whole carpet.
My daughter's chest freezer quit working on her and some meat thawed out. The blood leaked out of the unit and got on the carpet. She tried shampooing it up, but the smell and stain are still there.