Win 7: Black screen on boot up, before login screen?

How are you loading the System Recovery Options? System Recovery Options

Can you get to F8 menu (Advanced Boot Options - Advanced Boot Options) and select "Last Known Good Configuration"?

Also try "Enable Low Resolution Video (640x480)" after that.

I am able to use the "Repair Your computer" tools after pressing F8 during booting only . All other options leads to Black screen with cursor in the middle

Last Known Good Configuration leads to same

Enable Low Resolution Video (640x480) leads to same

See if you can actually open a task manager in black screen.
- Check if explorer.exe is running and start from CTRL+ALT+DEL (task manager - new task)

- Also try loading defaults in BIOS

CTRL+ALT+DEL & Windows Logo Keys are not responding on Black screen.

What do you mean by "loading defaults in BIOS"? Is it a hardware reset?

Will it cause loss of Hard Disk data?

I did search in this forum.

The threads talked about additional issues upon BIOS reset. Am I heading there?

I ran the SFC again. I am attaching the zip file that contain CBS.LOG & [SR] tag extract (xxx.txt).
I did not any find ERRORS there, SFC ended with message saying "found corrupt files but was unable to fix some of them" . It is misleading. There is no [SR] tag pointing to corrupt files.

Does SFC through false positive like this?

I ran chkdsk. Results

File verification completed.
0 bad file records processed.
0 EA records processed.
CHKDSK is verifying indexes (stage 2 of 5)...
Index verification completed.
0 unindexed files scanned.
0 unindexed files recovered.
Windows has checked the file system and found no problems.
0 KB in bad sectors.

Failed to transfer logged messages to the event log with status 50.

Try scanning the harddisk with Windows Defender Offline - What is Windows Defender Offline? - Windows Help

Leave BIOS reset for later (it won't affect anything on your HDD but may require some confuguration "only if" you had changed settings yourself before.

Edit: Did you have Service Pack 1 installed on your PC? It looks like you did not..

Thanks. I tried Windows Defender Offline. picked ( 2nd option ) On a USB flash drive.

I am getting "There was a problem formatting selected USB flash drive" Error Code 0007-80004005

I tried with different Flash drives. All gives same error. I manually formatted (FAT, NTFS, ...) the USB drives. Result is same.

I searched this forum. There are threads suggests to ISO format for USB.

How can I make this work?

Ok, re-run the downloader, but choose the 3rd option - As an ISO file on a disk (Advanced)
Download and run Rufus (https://rufus.akeo.ie/)
Select the USB flash (Device), the ISO file (CD icon midway down on the right) and click Start.

Then restart PC and boot with that USB flash drive.

Thanks. I created WDO on CD instead of USB.

I used this CD to boot the infected PC. I ran the scanner. Here is the outcome

QuickScan - It did not find virus/Malware
FULLScan - It did not find virus/Malware (it took 4+ hours)

I back to square one

What else I can do from here?

Tried check disk yet?

Disk Check - Option 2 for you
Make sure you are selecting the correct drive letter. D in your case?