i heart the sound "koh koh "from the hard disk .when i was opened the harddisk ,i saw the pin Cant read the disc.what can i do



Opening a hard drive doesn't mean it will be unreadable every time. I've opened and closed dozens of harddrives and still be able to read data off of them. I've even transplanted platters from a dead drive to another and been able to recover data this way.

@OP: As my previous post mentions, back up the data if you can. If you can't you are likely out of luck.