Computer wont boot shows nothing after press on button

Hello,

I have an HP Cpu
Fans are rusted but still well
Problem is
It wont boot. After i press the power button the green light shows up but
Theres nothing on the screen and the keyboard and the mouse mouse dont light up.
It was working in the morning but it freezes when after the windows welcome sign is done, but after the freeze it gets back to work.
Thanks
Allen