So I've recently built a new PC in which I have used an old SSD from my previous build. I haven't installed a fresh version of windows 10 but just used what is already on the SSD. whenever I turn on my PC it always gets past the motherboard splash screen and on some occasions to the windows 10 login screen, at which point the time and background will display but I wont be able to interact any further other than moving my mouse around. I cant even Ctrl+Alt+Del or use the shut down/restart/sleep option. occasionally instead I'll get a blue screen saying my PC didn't boot correctly. I have tried using windows automatic repair and it tells me it couldn't fix the issue. I have tried booting in safe mode but when I type in my password the loading circle appears below and then my PC proceeds to do nothing. Another time upon starting the PC had a blue screen with a loading symbol and then proceeded to do nothing. One time near the beginning my PC managed to boot up properly but it refuses to do it anymore. I stupidly didn't back up important files I need when I had the chance and I don't want to lose them if possible by having to reinstall windows. Any ideas?