I played the game last time about 2-3 weeks ago.

I had progressed quite far and was around lvl 50 or so.

I decided to play a little again today, only to find that everything I has done was gone.

When I started up the game I got a popup window saying that the game had to detect my hardware as if I has just installed the game and was playing for the first time.

I found it a bit odd, but didnt think anymore about it.

When I got into the game I discovered that all my savegames was gone

There was no indication whatsoever that I had ever played the game before.

What I would like to know is how the hell all my savvegames and all my progress can just disappear like that.

I have done absolutely nothing to the game since last I played it, but still all my progress is just gone.

I have never seen anything like this in any game I have ever played before.

Has there been any recent updates to the game that has caused all my progress to be erased?

evil familymembers? different useraccounts? the game stores them in "Documents/My Games/Skyrim" on windows together with ini files. Never heard of the game willfully with artificial intent devouring any saves. And backup. I have like 12gb of saves backed up for a boring rainy day. Really check your user account folder that it is the same as always and nothing else missing.

Since I live alone, I am the only one who can mess with my computer, and I know I have not deleted them.

Having one account I cannot possibly have used the wrong account either.

I assume you mean Steam account as I have never heard of a non steam version.

I just checked the folder you mentioned and the only savegame files there are the ones from the new game I started as a result of the missing files.

Could the cause of the problem be in one or more of various mods I have installed?

I have a number of mods which are not working either anymore.

Some are animation, but most are armor/clothing mods.

Used to have mods with all sorts of craftable armor, clothing and jewelry which no longer works.

Like you I have never encountered something like this before either.