I want to know the different way to check wether CPU,Ram and Motherboard is working or not without any special instruments

Can you boot into the BIOS? If so, most have a verbose setting that will show you all of the POST (Power-On Self Test) output. That is the system doing a sanity check of the things you noted in your post. If they all check out and the system still won't boot, then you probably have a system disc problem. If you can't boot to the BIOS, then likely there is a CPU or motherboard problem.

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