Don't Panic
One cause may be a dead CMOS battery and the BIOS reset to default.
F2 and check the BIOS. If it's set to Legacy and Raid instead of AHCI and the date is somewhere in 2007, the battery is probably dead.
Window's 11 can run on legacy boot but it's a little risky and doesn't always work.
What to do.
1. Install a new battery
2. Create a Windows install bootable flash drive.
3. Open the Gemini app on your phone and tell it what is going on.
You are all set. Do what it tells you to do.
Good Luck
Gemini and I fixed the boot sector and BIOS settings once. I noticed the date problem and reset it but didn't' bother replacing the battery. In the old days we could just F1 and continue to boot. Those days oar over. After a fer weeks it happened again. I had to do it all over but this time I replaced the battery.