In the searching I did before posting my problem, many people suggested contacting my host, which I am doing. In the meantime, though, I thought I'd ask for help here in case there are informative threads I missed.
Starting this week, the comments, archive and next page functions on my blog no longer work. Clicking on any of these catagories yields:
Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.
Please contact the server administrator, email@example.com and inform them of the time the error occurred, and anything you might have done that may have caused the error.
More information about this error may be available in the server error log.
Additionally, a 500 Internal Server Error error was encountered while trying to use an ErrorDocument to handle the request.
The only thing I can think that I've done was to change to change the URL of the blog address to go back to my homepage. I didn't like what it did, so I changed it back. I can't imagine this had an effect on my comments, etc, but throwing it out there.
My site is http://www.standsalone.org/blog - please enjoy a humorous story about my math teacher in hs if you visit.
Thanks for any and all help!