Pc not coming on

Check the debug LEDs on your motherboard. After you press the power button, the PC would attempt to boot, and there should be LEDs lighting up to indicate a specific component is being checked. Usually if a PC fails to power on, a LED would stay lit, indicating a corresponding component has failed. A picture of the LEDs when you press the power button would be nice
here's a website that explains more. https://kb.aftershockpc.com.au/computer-...

If none lights up, though, consider checking the power supply and the cable to see if anything has failed. It would be helpful if you can tell us what did you do the last time the PC booted normally, and share more information about your specs(what is your CPU and GPU's model, ram, motherboard, hard drive or SSD).