How do you know if an IC is damaged or just doesn't work anymore?

I swear that I wired an inverter the way it's supposed to and it simply doesn't work.
I have tested it with LED lights (and no, i'm sure it's not the LED lights)

How do you know if it's me or if it's the IC?
Also, what kinds of things can damage an IC and cause it to not work?
2 answers 2