external hard drives not recognised

A problem has recently shown up.
I have a lot of data archived on Seagate external hard drives.
Recently, every single one has failed to show up and be accessible in This PC.
They appear in Device Manager where they are each described as "Seagate Expansion Desk SCSI Disk Device" (same description for each drive.
I've recently fitted a new modem from my iSP which has some teething troubles but don't think this can be the course.

Another problem is that system restore has never worked on this - my main Desktop. Although about 5 years old now, it still handles most of my stuff.

I am thinking of biting the bullet and doing a completely fresh install of Windows (it is running the latest update - 10 Home 20H2 OS build 19042.804) to get rid of a lot of accumulated junk apps etc.
But it would be great to be able to access these drives on this PC before I do that - I've got hours of pages to produce in Word and it would be great not t have to copy stuff over from USB memory sticks - which incidentally show up on This PC and are accessible for read/write.
if anyone knows a quick fix, it would be great.

Reboot the computer > open the BIOS > take pictures of the drives > post images > boot to the desktop
List of PC brands with their corresponding hot-keys

Open device manager > click view > click show hidden devices > expand disk drives > post images

Open file explorer > this PC > post images

Open disk management > by default some columns are compressed > widen each Status and Volume > make sure the contents within the parenthesis are in full view and that none of the characters are cutoff > view disk 0 > widen this row as needed so that all of the characters are in full view > post an image into the thread
https://www.tenforums.com/tutorials/...creenshot.html

Download and install Minitool Partition Wizard > click launch > post an image of the results into this thread
MiniTool Partition Wizard Free Edition - Free download and software reviews - CNET Download
MiniTool Portable Partition Magic Brings Easier Disk Management

Hi,
These solutions are at the limit of my comfort zone and I was hoping for an easy mend solution.
I've a dozen or more external drives - originals and copies - both powereed and portable. They all work fine on a backup desktop and my laptop. It's the main 'workhorse' desktop that's the problem.
Is there a quick diagnosis or fix, given that the drives are OK? Both desktops were bespoke builds.

Run through these Seagate troubleshooting steps:
USB External Troubleshooter | Seagate Support US

This is NOT, I repeat, NOT an issue with the drives. Every one of them both powered and portable, perform faultlessly on other PCs and laptops, connected by any of the cables I've used. What are the chances of all of them suddenly developing the same fault?
The problems are on this one desktop PC only and would therefore logically seem to be either hardware related or OS related. All the USB3 ports are OK (ie they happily recognise memory sticks, card readers) so problems with cables and ports can safely be ruled out - yes?
Which means a fault further in, on the m/b - or (my suspicion) something inside Windows 10.
Is my logic at fault?
If not, has anyone any ideas on what can be u/s on the m board or in the operating system? I really want to avoid the hassle of reinstalling Windows but it's beginning to look like that may be the choice with the best chance of success.

Hi,
I thought of this, but weighing up the pros and cons, I think I'll do a complete instal of win 10 from the media creation tool. I'll use the opportunity to do an inventory of everything installed and have a good clean out. A look inside won't come amiss either! 4 -5 years ago I ended up blowing/vacuuming a ton of gunge from the interior!
But all this will have to wait until more urgent jobs are done and I have half a day to spare, - which is why I as hoping someone might have known of a 'quick fix' solution.i suppose there's some consolation in knowing that there doesn't seem to be one.

Just 2 quickies. Do you mean a clone or an image? I think I understand the difference immediately afterwatching YouTube 'how tos' on it, but a month later I'm back to head scratching. And should an anti virus be added - or anything else before using Macrium or should it be done as soon as the OS is on, even before tweaking the appearnace of the desktop?
The last time I did this I started by deleting and merging all the partitions on the ssd before unleashing the media creation tool created Windows OS on it. Is that necessary or does the OS do it itself?