Email - Unable to send or receive

I can receive email on the Cox web site but I can't connect to my email account with Thunderbird or my android phone. Up until a couple of days ago both Thunderbird and my cell phone worked perfectly and have for the last several years. The only thing that has changed is that I had to change the password on my router, but I don't see how that could have made a difference. Also, my wife has a cox email account and uses the same router and she is not having any problems. I've done everything I can think of to fix the problem and any help would be greatly appreciated.