ok, engine makes weird sound and trans. sounds weird in 1st/2nd gear high rpms

hey guys, need some help on this. Still doing it, really wanna sell it fast so i dont get jammed w/ paying a grand for tranny,clutch, installation and stuff. I was told it could be preignition...what is that and how do i fix it? What i have been told is to replace plugs,wires,rotor,cap. I did all that but my rotor can't go on cuz the screw is messed up and i dont have a tool to get it off. Well, any help is greatly appreciated. Thanks