is thunderbird having problems

all of a sudden I'm not getting any new emails and some of my emails that I got won't come up or unbold. I didn't do anything to the program. I haven't fooled with it. I saw there was an upgrade recently from 154 to 155. when did this happen? I have 5 email accounts on my desktop and the emails are doing funny things. Now they finally loaded but they aren't coming up or unbolding in one of the addresses. In another address I was able to pull up the emails and they unbolded but then all of the new ones bolded again and I couldn't pull the last two up do you have to contend with Windows upgrades? Do windows upgrades affect Thunderbird? I don't 'fool' with my computer as I'm not very computer literate.