Arduino isnt found on COM port

So I might have broke my arduino board by leaving it around magnets but I'm not sure. I bought a new board and it connects and shows up on my computers device manager and everything works perfect. My old and maybe broken board shows its getting power but isn't showing up on my device manager and greys out Tools>Serial Port in the arduino program... Is there a way to fix this or Is that board toast? And also can I still use it for something if its half broken?

Magnets are probably irrelevant.

What is the "old" board, where did you buy it, and what was the last thing you did with it?