I'm using Windows 10 and Windows Live Mail.  WLM is connected to the AOL mail server.  Today for the first time, the message headers are missing for about 25% of my email messages.  For the email messages that have a missing header, the reply key is grayed out.  I've never seen this problem before.  Please let me know if you have an idea of what's going on, or better yet, a suggestion for what I can do to fix the problem.

Thanks for your help.