Laptop display back,but sound,wifi,dvd Gone

I have compaq f739 laptop, some days before it was having problem with display, it was working but there was no display at all. I opened it checked graphics chip and put a paste and gave it hot air( all material euipments i gathered from a mobile shop) and then display started to come. But since then there is no sound, no wireless card detection, no dvd drive detection.
What could be the cause.