Re:I recently got a USB and put in the latest windows 10 iso in it but it doesn't seem to have a way for me to reinstall windows through the USB because it always writes remove USB and media devices if you just put Windows.iso on the usb, that does not make the USB bootable.  Since there is no bootable OS on your hdd and usb, PC tells you no operating system found.  Copying the Windows.iso file on a device does not mean the device automatically has an operating system.     you can prepare a bootable USB containing Windows 10 installation software by going to Microsoft site and click "Create Windows 10 installation media".  Download Windows 10 (microsoft.com)  
Hi guys my Dell Optiplex 780 Pc has been on black screen for some time now, it keeps on writing operating system not found, I tried getting into the Dell Bios settings nothing seems to be helping, I recently got a USB and put in the latest windows 10 iso in it but it doesn't seem to have a way for me to reinstall windows through the USB because it always writes remove USB and media devices, please help
Dell optiplex 780, operating system not found