how do you get out of the plane sphere???

*Spoiler*

On the lowest level of the sphere is the engine room. You will need to get a demon's heart in order to power up the sphere and return to the Prime material plane. To get the demon heart, however, you first need to defeat Valygar's uncle. Once he is near death, he will take the sphere to a plane where you can get a demon heart. After bringing him to near death, exit the sphere, you will be in the Abyss. Kill a demon, get its heart, and return to the sphere. place the heart in the engine, talk to Valygar's uncle again, and you will be able to leave the sphere and go home.

Well I got to kill the demon an return to the prime I freeded the knights but Lavok won't talk to me he stays hostile and nothing I can do makes him change

Do you still have Valygar. Is Lavok injured and lying on the floor?

Yup I still have him and Lavok is on the floor just lying there dosenÈt talk and takes punishement without dying!