Jono106, try putting the computer back to where it was before the trouble began, that is - the original processor, memory and soundcard, ensuring that all the connections are correct. If it doesn't work then, you may have something damaged.
You are referring to "the company". Can you elaborate on that. If the supplier of the computer advised you to fit the incorrect parts then they may have some responsibility for giving bad advice.
Have you checked that you put the additional memory in the correct slot. Some motherboards are fussy in that respect.
Finally can you tell us more about your computer. What motherboard do you have, what was the original processor and memory, and what did you change them to.