Unable to boot into Windows - Disk Corrupted

I have a DELL Inspiron 17R SE 7720.
I was running Windows 10. A couple of weeks ago or so, I installed some Windows updates. Immediately after the update and subsequent restart, I noticed that my Disk usage started to fluctuate wildly, spiking with considerable frequency to 100% and then coming back down, before spiking again.
I tried to reboot my laptop.
However, when I tried to reboot, my laptop wouldn't boot into WIndows, after a long time trying to boot up, it gave me a message saying a device is not found and I should use a recovery or repair disk.
Using the Microsoft Media creation tool, I created a recovery disk on my USB and made it bootable using Rufus.
On my laptop, using my BIOS, I changed my boot to Legacy from UEFI, to enable a boot from USB.
After plugging in the USB disk, I tried booting up from there, which happened successfully, I then tried one of the repair options, i.e., trying to reset my laptop keeping the files. Unfortunately, it said that my Disk was locked and hence a reset could not be performed.
I tried the reset option again after a reboot, but I got the same error message. I then tried to bring up the command prompt with "Shift + F10" on the repair screen, and tried the following :
CHKDSK /R
This reported that the Master File table is corrupt and that it was unreadable, and it would try to get it from the file system. Unfortunately, after waiting a really long time, it failed to get the Master File table.
Subsequently, from the Command Prompt, I tried the following :
BootRec /FixMbr
BootRec /FoxBoot
These operations completed successfully, but as I was to find out, did not help at all.
I then tried the following BootRec command..
BootRec / ScanOs -This told me that there were 0 OS installations
BootRec / RebuildBsd - This also told me that there were 0 OS installations, and would not proceed.
I thought to navigate to the boot folder and rename or remove the existing boot record, in case it was locked or hidden...
So I tried to navigate to
C:\Boot - from the command prompt, but it said the file structure was corrupt and unreadable.. I got the same response if I tried to navigate to any folder on the C Drive.
My disk was functioning normally till the time I installed those updates. I don't think it is a hardware issue, even though my laptop is 3 years old.
I have no idea what can be done now. Apparently, there is no restore point.
I do not wish to re-install Windows, I had a lot of data on the disk, which I do not wish to lose.
Kindly advise.

Thank you. I shall try this and let you know. I am concerned because my disk is coming as unreadable...I do not wish to lose any data.

topgundcp said:

On the screen in step 3 above. On the bottom, there are icons for Command Prompt, File explorer ...
Use File Explorer and try to open C Drive to see if you can save your data from it to another HD, if not try chkdsk /r again, it will take a while to complete depending how corrupted it is.

I tried the steps above, but with with very little success.
Even though I made the disk bootable with Rufus the way shown above, booting from USB was absent as an option in my BIOS UEFI boot options. Even when I wanted to create a BOOT option with USB under UEFI, it did not detect my flash drive.

On the other hand, it was perfectly visible in Legacy. So I turned Legacy options on, keeping UEFI Boot option. Aafter reboot, I chose the USB option from legacy. It allowed me to head over to the screen from where any of the above options were possible.

From the file explorer, I could not navigate to any folder within C Drive. Also, it did not show me any properties from C Drive. From the boot option, it failed to detect any OS installed anywhere in the system. However, I asked for a boot fix. Eventually that didn't do anything.

I used the command prompt to run a CHKDSK on C Drive. I got a message saying Master File table is corrupt and that WIndows will attempt to retrieve it from the file system. Unfortunately even after keeping it for 8 hours, nothing happened on this.

When I rebooted the next time, instead of saying that WinLoad.efi is missing, it said some other file within boot cannot be found, and repeated the same advice of using a repair or installation disk.

Any further suggestions, please? Is it a Disk issue? Would it change if I somehow manage to load from USB within UEFI, if so, I'll ry and see how I can make the USB visible as a boot option for UEFI.