external drive issues Help!!!!

Hello peoples i need some help so here i go.......

ok i have a 500GB NTFS external WD drive and its full (theres only like 20GB left on it)
and for some reason everytime i enter a folder on there that has all my videos a little window will pop up and say (Can't read partions do you want to format)
but only when i click on that folder...

i can click on my pics and music and everything else but that one folder,
And last night everything was working fine on it...i didn't turn off the pc or unpluge the drive by Accident or anything

It says the folder has nothing in it but it should have about 420GB's to 450 GB's worth of data in it....



I used the error checking on the disk but right when phase one ends it says (Windows can't finish checking the disk)

I had a program a few ago and had it scan the drive but can't remeber what it was....but when it scaned,it said that there was (Linux ext3) partions or sectors on it or something i don't really know but i never had this drive on a Linux...

but if thats the main problem is there a way to turn back those to whatever windows uses..???


Please Help

thank you

tylor