NIS won't open

I just bought a brand new Dell.  I activated the NIS and then began installing a variety of new programs.  I installed a Logitech webcam which required that I turn off my virus protection and my firewall.  I did and then installed the webcam.  I tried to open the NIS program to turn everything back on and I can’t open the program.  I restarted the computer.  Nothing.  I unplugged the webcam.  Nothing.  I restarted again.  Nothing.  Now all my protection is turned off and I can’t do anything to turn it back on.