looks like the disk that you have your OS on might be broken or something happened to the OS on the disc. Looks like you have to reinstall your computer. It's hard if you don't have any experience. If you want to install windows 10 then get a 8 GB or more USB, download a .iso file from Microsoft on Windows 10 64 bit. Plug it in computer, spam f2 or f10 after you turn on your computer, put the USB as boot from USB, or boot first from USB, then boot it again, and install windows 10 on your disc. If you only have one disc then this can work as a diagnoses if that disk even works anymore, if you cant install on that disc, then you have to replace that disk my friend.