Skyrim.esm and Update.esm are missing from my Data Files. I'm not sure why this is happening. I did try to verify game integrity, but that solved nothing. I did change the plugins.txt file and I did add 2 new lines with the esm files, but that didn't fix the problem. I did the same to loadorder.txt. NMM is able to display the esm files correctly....

After Googling the problem it seems that it has happened before. I can't find a solution though. And no, the files are not missing. They are still present in my /Data/ folder.

Nexus link: http://forums.nexusmods.com/index.php?/topic/978903-mods-not-loading-anymore/

They're not supposed to be in the Data Files screen.

They used to show up. My mods aren't even loading anymore.

Again, it doesn't matter. They are hardcoded by the game to load up automatically. Even if they do show up in the Data Files screen, it won't change anything.

I just can't figure out why my mods aren't loading anymore. DLC isn't even loading.

How many mods are you trying to load?

230-240. Somewhere between.

There is an upper limit of plug-ins that you can load - 255, and the Skyrim, Update, and DLC .esms count against that as well.

Yeah, I know. I'm trying to fix it but it's rather hard. I doing a new-ish install. I'm keeping many old files and removing stuff. I'll be done tomorrow. Hopefully it'll work.

Crazy, hopefully you are using Wrye Bash and will also start a new game upon changing/removing your not "must-have" mod selections.

I second chuckos, Wrye Bash is a necessity in your situation. Attempting to manage that with NMM must be a nightmare.