Ok, I know this is a rookie oopsy, but what can I say.

I went into the Proudspire cell to look at materials, and apparently moved something. *crap*

I need to know how to replace the proudspire cell in my mod with the one from the masterfile. Or if you have another method of helping me fix this, I would appreciate that too.

Thanks.

I couldn't find a solution to this either. Ultimately what I did was just reloaded the data files without setting an active file, duplicated the cell I was trying to mod, saving it as a new esp, and then just used that one. You'll need to manually replace any custom objects you have, though.

I found that this always happens to me if I go to a cell and right-click something in the render window, that seems to be a sure way to mark it as edited. So I just select it in the render window, and then right-click it in the cell's object list, and that works just fine 90% of the time. Otherwise, just save often in case something gets messed up I guess.

Ahhah, that is very helpful. Thank you.

when you are on the screen where you select the data files to edit, select your mod and hit INFO. This will bring up a list of changes made in that mod. Look for the entry for the item and/or cell that you accidentally changed, and press delete. This will toggle the IGNORE flag. When an entry has the ignore flag, it will be removed the next time you save that mod.

Alternatively you can download the Fallout Mod Manager for Fallout New Vegas. It comes with a utility called TESSnip which does basically the same thing as the INFO menu, but it is organized a lot better.

This solution, to http://cs.elderscrolls.com/index.php/Mod_Cleaning_Tutorial, is related to Oblivion, but it′s exactly the same technique.

If you have no knowledge about the ESP-data-format leave your hands off TESSnip!
TESsnip is a great tool and let's you manipulate ESP's in many way's ... nuking your ESP unrecoverable as well.

Thanks all. Info has been super helpful.

bah TESsnip's not that bad. Definitely make a back up before you prance around in it though. In fact, make a back up before you delete entries in INFO as well. You can never backup too much.

Yay, I fixed it! Thanks folks, appreciate the assistance.

In the meantime I've found a TESsnip derivate: http://skyrim.nexusmods.com/downloads/file.php?id=5064 [https://github.com/figment/tesvsnip#readme] (thanks to PlanB from the http://www.scharesoft.de)
It′s a stand-alone-tool, similar to the TESsnip, which is shipped with http://fallout3.nexusmods.com/downloads/file.php?id=640.