All you know right now is PC did not complete POST (power on self test).
It might be the power supply. But it could also be some other problem.

->No way to tell from your description what the problem is.
Do you hear any beeping?
Computer POST and beep codes

If you computer does not have a motherboard or case speaker you may need to get one.
Check your motherboard manual.

How can I disable or enable the internal speaker?

Motherboard speaker: