OK so I'm officially at a loss of what to do. A bit of backstory, I'm helping a friend of mine build his very first PC and we've run onto quite the snag. First of all, the motherboard that he bought didn't support the new generation Ryzen CPU that he had and required a BIOS update, no big deal. I moved my CPU over to his build, downloaded his OS onto his SSD, and updated the BIOS of his motherboard. Everything was going smoothly, we were actually on the SSD using Windows! However, I then took my CPU out and replaced it with his, and the PC boots, but the SSD has suddenly disappeared from the boot order and cant be seen. WHY? no clue. The weirdest bit, is I can go into windows recovery using the USB that had the OS on it originally, and we can access the command prompt on the SSD! I've checked the cables and plugged into different ports on the motherboard but to no avail. Has anyone had this issue before and knows what on earth is going on?