Help! clay won't bake!!?

ok, i made this really cool cheetah out of what i think is sculpey clay. the clay was all ready really soft. and whent i finally got it perfect, i tried baking it like i've done before many times. after about 10 min, i checked it and it had fallen over and everything was sticky and melty. i soon fixed it and i wanted to put it in again, but im afraid it will be ruined. Why wont my clay harden?and it's not the kind where u leave it out over night and it hardens. Are there any other ways to harden it?