Flashing folder with ? Can’t turn on computer

Yesterday when i tried to turn on my computer it shows up with a grey folder with a question mark. I tried launching into recovery mode and repairing all the stuff in there. Everything gave me green check marks. Then i tried to reinstall my OS system but it said there are “no packages eligible for install. contact the software manufacturer for assistance. why the installer and try again.). I tried turning off the wifi and trying again but no luck. Do i need to replace something in my computer or is this a technical fix?? i’m honestly TERRIBLES with tech beyond the basics. Please help haha