Cubase Elements 9 - Audio is not working

So, my Cubase is basically useless at the moment.
After I turn on my Cubase for a while, the audio sensing thing on the bottom right of the corner shows that Cubase isn’t receiving and emitting any sound. This also happens when I try to play an instrument through my keyboard. All of sudden, Cubase can’t receive any signal from the keyboard, nor any sounds that I make. However, when I tried playing a random song from youtube, it worked perfectly.

P.S. I have tried all the management setting stuff that the forum/internet provided.
Please help TT TT

Hi and welcome,

I would probably try to go to the factory settings by starting Cubase in Safe Start Mode.