Mozilla not working at all

Hello,
My Mozilla firefox is not working and I don't know why, I have reinstalled it a couple of times & it doesn't seem to help, it keeps saying Neterror and it will not even load the page so that I can see what is wrong, can my firefox be wiped out or blocked for some reason? I have never had this problem before, I have had this problem for a couple of days and I would like to know what is wrong. please tell me what I can do to get it back.