Hi i accidentally used an incorrect sata power cable on my hdd's, (its a evga a thing i guess). Anyway i switch the cables to the right ones and noticed that one of my drives was no longer being picked up by my system and there was also a distinct burnt plastic smell coming from my hdd. so after further inspection i discovered this broken doodad and figured it was the reason why this drive is no longer being powered on and just wanted to ask if i should replace the whole pcb or is it possible to buy this part off the web.

There's be a rash of these lately. https://forum.hddguru.com/viewtopic.php?f=1&t=38032

That's a diode You need to checked the fuse to the right is intact. Can you post a full picture of the PCB so we can check if the magic smoke escaped from anywhere else.

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Wow its also a Toshiba drive, doesn't surprise me that my Seagate drive survived. anyway here are the rest of the photos

The component is a Schottky diode.

RB161M-20, Rohm, Schottky barrier diode, 25V, 1A, marking 72, SOD-123:
http://rohmfs.rohm.com/en/products/databook/datasheet-nrnd/discrete/diode/schottky_barrier/rb161m-20.pdf

The failure mode indicates that the 5V input was subjected to a reverse voltage. If the diode is shorted and the fuse is intact, then there is chance that the rest of the PCB, and preamp, survived. If the diode or fuse is open, then the preamp is probably dead.

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A backup a day keeps DR away.