Touch screen not working properly.

My N7's speakers were not working properly so I decided to open it and see if I could do something about it. After opening it I realized that they aren't functional and that I could not have fixed them. Note: I didn't touch anything except the speakers.

After putting my device back together the touch screen has gone haywire. Sometimes it starts operating itself as the menu button is pressed automatically, sometimes it does not respond at all and sometimes which is very rarely it works fine. I live in Pakistan and the N7 is not very common here so I do not trust the local technicians here with my device.