I have 2 Hardisks in my pc,  one is 2Tb and the other is 350Gb. So at first these two were connected to the motherboard. But after 6 months my computer started get slow. 350Gb hardisk stoped showing files and showing files when restarted. Then i unplugged the 350 gb hardisk. Then the pc performance was restored.

I am just a 15 year old beginer video editor, i dont know much about hardware. Is there a way to fix my 350 gb hardisk?