During the recent storms, my modem crashed and was replaced by Comcast. Since then, I cannot connect to my cameras. My installer says I need to open port 80. I can access the modem, but thats where my knowledge ends. Can anyone help?
You probably need to do a port-forward from the outside port 80 to the inside dvr the cameras are on, and your dvr/cameras should be statically numbered, etc. This isn't a job for someone who isn't familiar with the hardware or with networking but it is very simple for someone who is.
Your camera installer sounds like a dweeb. Is he seriously too lazy to come out there and spend 10 minutes logging into your cable modem and setting all this up again? Find a better camera installer who understands customer service. And buy a decent UPS that will protect your gear and put your cable modem on it, your installer should have told you to do this when all this was setup.