External Hard Drive Malfunction

so I was screwing around with the permission on an external hard drive trying to get overall permissions to all files . i deleted the permissions for the g: (external) drive and now the remove drive icon pops up when i connect the drive to my laptop and my computer but the auto play does not pop up, the disk does not pop up under my computer, it appears as unknown devicde under device manager, and i can’t open it.. i looked under system something and it said that the disk was unreadable… my question is how can i fix this?