I reset my password on my server, so need to update my password on thunderbird. I removed all of my passwords using Tools>options>security>passwords>remove all. Then turned off thunderbird and rebooted the system. Now when I open thunderbird, it simply doesn't connect to the server. It never asks me for my new password.

I use Dreamhost, and there have been some problems with the certificate. Not sure if that could be related to the problem.