memyselfandI

Hi, i have a HP Simplesave external hard drive that i'm using with my PC. i wanted to prevent my kids from changing names of files and moving them etc. so i right clicked their folder, chose security tab and for user Everyone i unticked full control. to cut a long story short, i had problems getting into the folder and subfolders, tried to change owner etc, but videos were showing access denied in real player. the subfoldrs had padlock icons on them (some but not all) so i tried copying the folder to my desktop and the folder that was copied had no locks. hurray! or so i thought. i deleted the folder from the hard drive then cut and copied from my desktop back into harddrive. i thought i was really clever! however now i have a lot of files missing from subfolders. i ran a restoration program cos i'd emptied my recycle bin but they didn't show up, and the few that did restore but dont play. hope its not too hard to follow what happened... please tell me what i did wrong and where my files might be. thank you in advance