How do I fix my bass amp when no sounds are coming out?

'kay so I need help :l this is what happened...

Everything was perfectly fine until in a minute, no sounds were coming out from my amp. I checked to see if the screw thingy where you plug in both ends of the chord was loose, but nope; it was as tight as ever.
As a first step, I'd want to determine where the problem was... it's either with my amp, my bass, or my chord.

I came to a conclusion that it was the chord...when I bought a new one---6 feet long---and tried to plug it in, still no sounds are coming out. And before I bought the chord, we tested it out and it worked.

I thought that maybe it was the amp that had the problem so I plugged in one end of my chord and held the other end, then I could see the beats coming out from the speakers. And also, the "power" light is working.

Last thing is my bass...I don't know what might've happened to it D: I never dropped it or anything.

Anyway, I really need your help guys...thanks in advance (*^ O ^*)