view hidden files

I was looking at my 250 gig external drive. It says that 190 gig are in use but when i look at the drive at shows about 90 gigs between the three folders there. So where did the other 100 gigs go??

Just a wild guess but... Did you drag some files to the trash without emptying it? These files are not deleted and until you empty the trash they are still taking up space on the hard drive.

will it seems some of the files on the disk were from the pc and osx would not delete the folders.after i did a secure delete they are gone and i have my drive space back.

I'd also check iPhoto and iMovie Trash as they need to be independently emptied.