You're hosed (i think) unless

-- you're rich and you send the disks to a shop for megabucks (they may start with a trivial purchase of 2-3 identical model disks)

-- OR IF your problem was NOT the actual platters/heads, YOU obtain 1-2 same-model disks, swap the board from a replacement disk onto your hosed disk ( w/ sm torx tool and brave fingers )

I've not done this myself yet.

I HAVE had "stiction" problems where (after a power out or a "rest" so a disk bearing/lubricant gets a chance to harden) the disk just isnt spinning up. Of course, tapping/whacking it at the right/initial moment will usually cure that and you can feel if it's spinning or not....if you can hold it in your hand ...OR somehow get hands-on during powerup.