https://www.esoui.com/forums/showthread.php?t=8858
Just READ please, as the sticky posts contain all that information for you already. The "take Screenshot ingame" method is the simplest way to find the addon folder that ESO thinks it's the correct one.
And about "I did not change anything": ESO could change the folder by itself unfortunately so this is not a valid information here. Even if you did nothing, ESO or windows could have messed it up.