I deliberately avoid RAID and can't solve your immediate problem, but others here have experience.
Hang on for a while and someone should be along.
I can only tell you what I used to do a very, very long time ago, and make suggestions that might help you recover and have a probably better chance of avoiding a repeat.
When I last worked with RAID in Windows, software based RAID was only available in the Server edition. Storage pools didn't exist yet. But this same type of thing could happen.
This is just one of the reasons that the previous commenter recommended regular backups. Now there are services that you can subscribe to (for a fee, but it is not that bad) that will install a small program on your local computer and, with at least some of them, not just regularly back up your data to their own system over the Internet, but encrypt it locally on your machine before it is sent. I don't know if they can read it, but with the established reputable ones it should at least be safe in transit.
But this doesn't help you now.
There are two situations I have seen before that can cause your problem and others that could, but I don't have personal experience with. Either way, I would start trouble shooting this the same way. But I think that I should explain what I see as possibilities for what may have happened based on my admittedly very out of date experience.
If you are very , very lucky, this is a software / data issue. This probably means something went wrong separate from the hard drives and things got messed up on both of them because something was bad, incompatible, loose, or improperly installed or not fully compatible with your version of Windows but the drives themselves are actually ok . I have not actually seen this personally, but it could happen, in theory. I might not even raise your hopes, but you said that these hard drives are in an external enclosure and it seems logical to me that if a cable came loose or they were turned off before everything was finished being written to them it might cause what you have described.
If you are lucky but to a more normal level, in the process of getting pulled from a drive that was failing information was corrupted and jumbled before being written back to both drives. With the result that one is bad at the hardware level but the other that says it needs to be reformatted has some of the information, possibly the file system structure, jumbled. I have seen this happen.
If you are not lucky, then it is possible that both of the hard drives could be physically damaged. I am much more concerned that they could both have damage to the actual physical hardware because you said that they are hard disk drives and not SSDs, and because they are in an external enclosure. Just in case you don't know, hard disk drives have multiple spinning disks one above the other and read heads on little arms for each one. Each of these look a little like an old fashioned record player and work in a similar way mechanically, except that everything moves so much faster than a record player that it is hard to understand. So it all has to be lined up perfectly.
Dropping any hard disk drive at any time can break it. But (except to some degree laptop hard drives which are built and sometimes mounted differently) any kind of impact on a running hard drive, even just bumping it hard or moving it, can potentially damage it. It seems like modern high capacity hard drives seem to be even more sensitive on average than they were years ago when sizes were measured in megabytes rather than terabytes. So even though I have generally had good experiences with Western Digital hard drives, the Red series are their mid level drives, marketed if I understand correctly for workstations or less expensive servers. Not designed for laptops. So it seems like it would be easy to damage such drives in an external enclosure without even realizing that you did.
I would still try to recover my data however. I would try shutting everything down and powered off. Then carefully try installing the drives, one at a time if necessary, in a desktop as a second (and if there is room third) drive. You will need administrator rights . Ideally you want to use a computer with Windows 10. Then you just see if you can copy your data off of it. If you can't, but can at least see the drive, there utility software programs, including free ones, that might be able to get the information off of one of them. Some of these programs run in Windows, there are some for Linux that can rescue data from Windows hard drives, and some load from a bootable cd, blue ray disk, or flash drive if the computer you are using supports those.
I made my suggestions in order of increasing difficulty for the average user, and, unfortunately, increasing likelihood of working. If things are not too bad, you should be able to just use Windows directly. But in the (almost) worst case, as long as the drive will still spin, there are software programs, including some of the Linux (I think) and definitely ones requiring you to boot off external media (cd, flash, etc) that can overcome a totally corrupt file structure and read the raw data off of disks by directly accessing the hardware. But I am not aware of any version of Windows that allows this (I could be wrong) which is why you either need to boot into something or do it in Linux (maybe? I don't know if it still works in modern Linux).
The direct hardware access utilities used to be a pain to use, but there are probably better options now.
I would strongly advise you to research any utility before installing or using it to make sure that it is legitimate and not spyware, etc
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