PC Boots to BIOS: HDD recognized, no bootable media

Good aftermorning!

I've seen similar posts made in this subreddit. But the ones I've seen deal with PCs that are just put together and are within the first few boots. My problem is that while my computer is relatively new--I put it together in January, booted windows, I have been using it successfully ever since.

However yesterday, while using the PC, I noticed that the screen had a partial freeze. I could move/navigate the mouse, but couldn't click or otherwise interact with the windows environment. After about a minute, things returned to normal. I decided to shut off the computer because I was leaving home any way, and thought that might help resolve the issue.

But when I returned home and booted up, the problem articulated in the title occurred. Windows no longer boots. The PC goes straight to BIOS. In the BIOS screen, I see that the HDD is recognized. But it isn't recognized as bootable media, even though just until yesterday (for two months), it's been booting windows regularly and without *overt* issue.

Image: [HDD rcognition](https://i.imgur.com/GuXc8Jo.jpg)

Image: [No bootable media](https://i.imgur.com/fUEUlh4.jpg)