> I've had no other problems with it, even the day before this happened.
The same thing happened to me, with an automobile tire.
What you seem to have is a problem with the SSD.
I doubt that it is a problem with the computer's BIOS, or any settings within the BIOS.
When you pressed "F5", the motherboard tried to launch the diagnostics that were installed on the (non-responding) SSD.
Since the disk-drive was not working, that option was no help to you.
What I can't try:
1. Get it professionally looked at (No one looks or repairs PC's in my area)
2. Buy a new SSD (Can't afford a good one)
3. Test current SSD on another PC (Don't have another PC)
Ouch to #1. Do you have any non-professional friend who can help?
Ouch to #2. That very-much limits your options.
Ouch to #3. Do you have a family-member with a computer who can help? There do exist inexpensive adapters, e.g., USB-to-SATA that can connect to their PC and to your SSD, at half the price of a new SSD, that, I think, will just confirm that your SSD is "dying", and that you should have NOT spent the money on that adapter.
> Wimfsf.sys isn't found.
This is an indication that the file-system on the SSD is corrupted.
Imagine a book with a Table Of Contents that has been removed.
All the pages of each chapter are still in the book, but you cannot use the missing ToC to locate any chapter.
If it were me, I would purchase a new disk-drive, install it, install Windows onto it, and then attach the current SSD, to try to read all your personal files/folders (Documents, Pictures, Downloads, Music) from the "dying" SSD., while there still is a bit (pun intended) of "residual" life remaining for the current SSD.
There is no software that can "repair" (logically or physically) a "failing" SSD. It is important to copy what you can, while you can.
Yes, you need to spend some money for a replacement SSD.
For me, I had to purchase a new automobile tire, since "patching" the tire was not possible (nor safe) to do).
P.S. I know that some moderator(s) on this forum may object to me recommending any expenditure. But, given what you have described, replacing the SSD is the economical way to revive your computer.
The very-expensive alternative would be to purchase a complete brand-new computer. But, obviously, that is not what you want to do.