Many of my mods just disappeared!

I found out when I entered my game and received the notification that some items were no longer installed and was shocked to find my sim's mirror was gone. I then headed to my mods folder to see what was going on and many of my mods are gone. I have not played in a few days due to illness and so I have not removed anything from my mods folder. I have been playing since after the patch and they were there. Any clue as to what's going on? Some of these mods are irreplaceable (as in the creator has disappeared), but many have been updated...