Depending on motherboard, there may be led that will alert to the error, or ancient hardware will use beep codes. These are searchable and usually reliable, but I am not certain all boards have these features.
In order of easyness:
Try resetting the cmos.
Grab a USB stick and make a live USB of any distro you are comfortable with (Ubuntu if you aren't comfortable with any) and try to boot from USB. If that doesnt work, unplug any peripherals (pcie raid cards and such) and unplug all hard drives. If it boots, plug in the drives one by one until it doesn't. When booting stops, you ha e found the bad drive. If you have RAID set up then this process can get more complicated (but not much) report back if this is the case
Ram might be the problem. If you have a known working compatible set switch to that and check. If you don't have another set, consult your motherboard manual. It usually instructs to place 1 stick in a certain slot (usually the closest to the cpu but sometimes furthest). Test each stick in this slot. If you get a boot, add in ram until it refuses to boot, then you have found your bad stick.
If that doesn't work and you have a multimeter, the psu section has a guide for testing your rails in the stickies . While you have the multimeter out, test the cmos battery for good measure.