I had a tech from an IT support company come over to check out our computers. I guess I should have watched what he did more closely. In addition to several other problems, I just noticed that my "Recent documents" settings got changed. It now only remembers 9 documents (which is the default, I think) and all of my "pinned" documents are no longer in the list.

Can anyone tell me what he might have done that caused that to change so I can call the company to complain?

He probably reset your recent items in Windows. This is not an unusual thing to do and I expect it would unpin your documents as well. He also reset the number of recent documents in Word.

You can set this back under the Office button, Word Options, Advanced.
Under Display, the number of recent documents is set.

My god, you're right. It's also reset in Excel. Why in god's name would he need to do that? And why would he do it without asking permission?

And, how did he do it anyway?