most folks, and understandably so, are going to want some system specs before venturing down a specific troubleshooting path...
Some systems (those with iGPU capabilities) have more options available than others...
No display when powering on, however, can be as simple as a PSU, or as complex as any connected component shorting out the PSU preventing proper power on/POST, or, even the GPU (if a discrete GPU) might have died, which does happen...
However, I'd review a few Youtube tutorials on PC troubleshooting before getting in over your head, as even reseating components (or attempting to) or simple component swaps can induce issues if not done carefully/correctly. (swapping a PSU is not hard, but, be sure to use all new modular cables that came with the new PSU with the new PSU, as reutilizing even an old SATA pwr cable can burn out your drives, and reusing a PCI-e GPU supplemental pwr cable can burn out original GPU if at the first power on)
May try reseating a CPU, and then damage the socket and/or CPU in the process, massively compounding whatever the original issue was...