Hello and welcome Riuuiu that last message youy should just reboot the machinew and let it run the disk check.
If you can get safe mode then you type cmd in Start right click the small blue window > Run as admin > type in the little black and white screen sfc /scannow and hit enter.
(That is a space between sfc and the /scannow)
Another method which will show you the screen shots. Tutorial search - Windows 7 Forums