Why did my Mozilla Firefox stop working and how do I get it to work again?

One morning I turned on my computer and my Mozilla Firefox just randomly stopped working. I got this "Unable to Connect" error. I tried uninstalling it and restarting my computer numerous times. It is not my internet because Internet Explorer and Google Chrome still work. I can't stand either one of them and really would like to get my Mozilla up and running again. Please someone help me! Thanks!!