when trying to boot, nothing appears in

when I start the computer, I hear the disk spinning teh red light is on the case, no green light appears, I checked the video card and is fine, cables and power are ok, disk is working, memmory is ok, the computer was working fine, the disk was moved, but I installed it again with no os, Now I’m trying to boot from a disk to later install the os, but no check is done at start up.
can any one help me