I learnt a colleague at work my PC and he returned it to me. I got home and wanted to watch squid game o . i was greeted by an error message. I turned to Google trying to find a way to get past this but unfortunately i couldn't... Please, anyone knows how i can fix this on my own... Many thanks!!!

Start the computer and press F2 or what ever key instructions given to you to enter CMOS setup look for boot device and select your Hard disk or C drive to boot first in order of priority. Press F10 to save the setting or if in CMOS look for default setup button, I think it should be F9 to restore default set up.

Possible cause
1. Your friend might have used an external drive preloaded with windows/ operating system
2. Your hard disk/SSD might have shake/ displaced
3. Corrupt windows os.
However, first check Your BIOS to see if your hard drive is present/recognised,if yes select and try reboot.
If no, try booting from another bootable disk then reinstall windows to your drive.

corrupted windows boot manager, or disconnected hard disk or Ssd drive, reinsert the disk drive properly