WIN 10 (previously dual boot) : grub cli showing before startup (hdd is 1st boot option)

Question

I ' ve used my computer (dell) with both ubuntu and win 10 in dual boot, but I recently remove the ubuntu partition.

Since then, on every start, i've 3 times "checking media" message shown ( with "fail" after a few seconds) ; then a grub command line shows up, I have to type "exit" in order to access the following screen :

I select the first one and only then, windows will load.

I've read about the onboard lan options that could cause the checking media message, but the 1st boot option in my BIOS is HDD.

After removing the linux partition, I've removed from the bios a related boot option, but it did not solve the problem...

I tried to add a new boot option, but did not find any available file!

Any help would be precious, I try ot to attempt anything on my own in order not to get stuck with a computer that wont even be able to launch windows...

( I've tried restore factory default option, but no change )

Answer 1

This Answer is adopted from Dell Support for Windows 10, the same link provides a solution for other windows' too.

You can also do it from windows cmd mentioned in this answer

The GPT structure deals with a lot of the problems that the Bootsect command was designed to remedy in MBR. However if you find yourself in need of repairing the EFI bootloader, you can follow the instructions below :

If you do have the Installation Media :

Insert the Media (DVD/USB) in your PC and restart.

Boot from the media.

Select Repair Your Computer.

Select Troubleshoot.

Select Advanced Options.

Choose Command Prompt from the menu :

Type and run the command :

diskpart

Type and run the command :

sel disk 0

Type and run the command :

list vol

Verify that the EFI partition (EPS - EFI System Partition) is using the FAT32 file system and assign a drive letter to it (Assign a letter that isn't already in use.):

Type and run the command :

sel vol <number of volume>

Type and run the command :

assign letter=<drive letter>:

Type and run the command :

exit

In order to repair the boot record :

Type and run the command :

cd /d <drive letter>:\EFI\Microsoft\Boot\

Type and run the command :

bootrec /FixBoot

If you don't have the Installation Media :

Restart your PC

Tap rapidly on the key once the PC has turned on, but before the Windows Splash Screen appears.

Please be aware this may take several attempts. The timing for this option was shortened significantly from that in Windows 7.

Select Repair your computer from the menu that appears.

Select Command Prompt from the Advanced Options tab in the Troubleshoot screen :

Type and run the command :

diskpart

Type and run the command :

sel disk 0

Type and run the command :

list vol

Verify that the EFI partition (EPS) is using the FAT32 file system and assign a drive letter to it (Assign a letter that isn't already in use.):

Type and run the command :

sel vol <number of volume>

Type and run the command :

assign letter=<drive letter>:

Type and run the command :

exit

In order to repair the boot record :

Type and run the command :

cd /d <drive letter>:\EFI\Microsoft\Boot\

Type and run the command :

bootrec /FixBoot The next step is the same across all the operating systems at this point :

Rebuild the BCD store

First run the command below to backup the old BCD :

ren BCD BCD.old

Now recreate it using this command :

bcdboot c:\Windows /l en-us /s <boot letter>: All