Ok so I was making a vault mod then I was about to test it. I opened my FOMM then there was now ESP file so I thought of searching for it then dragging it to the Data Directory. That didn't work So i recycled it thinking it was a shortcut.Later on I checked if the file is there(search). it wasn't. So I Checked the G.E.C.K finding out it still has memory of it and every part is still there

So there are 2 questions:
1)How do you make the .ESP file appear on your Data directory. (FOMM)
2)How can I restore it or if not replace it.

Sounds like you forgot to run GECK as administrator. If you are on Vista or 7, your computer things the GECK is a virus trying to 'hack' or alter some files. Right click on the GECK desktop shortcut and click 'properties'. Then go to the Compatability tab and check 'Always run as administrator'. Then reopen the geck, load your file and resave it. Now it should save with full permissions and work.

Ok. Then where should the .ESP file located??

In ".../Fallout3/Data"

If you navigate to ".../Fallout3/Data" you should see a 'compatibility files' button on the top right of the window. You will find your mods in there.

If you plan on modding, its best not to install the game in the 'program files' folder. Or use 'admin' privaledges.