@Traruh Synred Actually, the ASCII code for blank is hex 20. Hex 00 would indicate something actually wiped the file. Or the allocation tables got corrupted, but in that case I would expect you'd have more trouble with your computer. Did you try a disk analyis & repair program? (and do analysis only; don't even dream of repairing anything until you have a complete, fresh clone of the disk somewhere safe).
Be that as it may; at this point about the only other thing you could try would be to inspect the disk blocks and see if there were pieces of your data around on that disk somewhere, using a block-level disk editor. Given the size of modern disks that is not a trivial undertaking; I have not done this for decades (literally).
I am not sure it has anything to do with SSD vs rotational media. Sure, SSDs are not infallible, just like spinning disks although they may have different failure modes. I really don't know; all I know is that I have had SSDs in my laptops for about 5 years without any problems. And I have had rotational disks that lived for 10 years or more; others failed after a year.
You are doing the right thing to look for a backup solution, and automatic is certainly the best and easiest. Whether an online solution is right depends on the amount you need to back up; personally I deal with TB (terabytes) of data so I use a local disk as any affordable internet solution would simply be impractically slow. A few gigs? No problem. Over the short term, however, any internet way to backup your daily work should work very well.
Sorry for not being of more help; but it seems all of us have to have such an experience once in our life. I lost a disk with weeks worth of data reduction and analysis as a grad. student; no fun at all. Life has its way of teaching us lessons...