after shutdown when I start it again then the pc not start. when I press the power button nothing occurred. I check the power button and the connection. all ok. I disconnect the cable of power button and start it manually by connect the pin but nothing happened. what I need to do?

I check motherboard. It got the power. any other way to check the power supply?

well i use a power supply tester,also use a regular amp tester ,so you could take it ans take to local repair shop and have them test it .
i have replaced a 100 or so psu that power fans and light but not the cpu

I use a power supply tester and it got power in motherboard.

I use a power supply tester and it got power in motherboard.

ok so now you have to troubleshoot things like ram,video card and other cards if any, and the cpu /motherboard itself and the only way i know how to do this is by removing them and try booting without or replacing them with a known working one