Touchpad not showing up in Device Manager

Hello,

I've a severe problem with my laptop. The DELL touchpad isn't working at all. I've tried updating the drivers etc, but when I went into Device Manager to see if it was showing up with a yellow triangle, I noticed that it was completely absent. I have had a technician out recently and he replaced my motherboard and cleaned out the system because of over heating issues. But now recently it seems the touchpad wasn't plugged in right. I still have a couple weeks left on warranty, so am wondering is this a case for another technician to come out to fix the error that the other technician may have caused? Or am I missing something? Usually by my book, once the device isn't in Device Manager, that usually means its not in right. 

Some help quickly would be greatly appreciated.

Thanks in advance.