Accidentally dropped a folder in N360 folder, can't put it back!

Hi,

i accidentally dropped a folder with music on the N360_BACKUP folder on my external drive. Now it says it has 0 bytes and i can't have access to it or copy it back to original place or nothing... It says "You need permission to perform this action. You require permission from admin to make changes to this folder."

when i try to change permissions in Properties dialogue it says "An error occured while applying security information to: G:\N360_BACKUP\Muziek. Access is denied."

 

What can i do to restore this folder?

Thanks for any help!