Having problems with Documents folder and One Drive, (on other threads).

This morning went to write and then save a file in Word 2010, only to find 'no files matching etc.' in the folder/file that I required. Went to see if I was looking at the wrong Doc. type and the expanded file type list was completely different from the day before! There are no option with .extn available, only Word Document at the top then others. I clicked 'Word Document' and this immediately populated my folders, so I had to save my recent letter with a Word Document type.

Luckily, this was fairly simple to do, but when did this happen, and why have Microsoft messed with file extensions causing confusion, for, what I can see, is no reason.

Found one work around from a few years ago which was very long winded and too difficult for me, saying if was caused by a virus, but I have several security programs running, and nothing to say I have been, or am infected, so very puzzling.

Any ideas please.