:BigSmile:

Windows 10 is on the system?

Yes, It is Windows 10 system.

After creating the Installation media,

1. Insert the Installation media (flash drive) into a USB port of the computer that needs to be fix. Power off system.

2. Power the computer on, quickly start tapping F12 key continuously  until you see Preparing one time boot menu in the top right corner of the screen.

3. At the boot menu, select the flash drive(Installation media) under UEFI BOOT.

4. In the windows setup, select your keyboard language.

You can now select the option to Repair Your Computer or reinstall windows 10 

I'd suggest you create a windows 10 installation media from the link below. You'll need a blank USB flash drive with at least 8GB of space and a good working computer to create media. Since windows 10 is already on the system, the windows 10 installation media should be free to reinstall or repair windows 10 on the computer that needs to be fix.

Download Windows 10 - microsoft.com

Thank you very much for your replies! Unfortunately, I still have problem to follow your instruction for booting the computer.

First, I have see the UEFI BOOT option in F12 menu. There are only show:

"LEGACY BOOT: Internal HDD (IRRT) CD/DVD/CD-RW Driver, USB storage Drive, Onboard NIC.

OTHER OPTIONS: BIOS SETUP, Diagnostics"

After I selected the flash drive at boot menu uner LEGACY BOOT, a message appeared as:

"Remove disks or other media. Press any key to restart."

When I press a key, the screen showing:

"Selected boot device failed. Press any key to return to F12 menu and chose a LEGACY BOOT or UEFI BOOT option. "

After pressing a key, the scree got back to the LEGACY BOOT menu.

How can I find out the UEFI BOOT option?

Your further reply will be greatly appreciated!!

Thank you again.

Please select BIOS setup in the Preboot menu (F12 key) or tap F2 key to get to the BIOS screen. Under the Boot tab, select "Boot list options", and change the option from "Legacy" to "UEFI, enable secure boot, save the changes (I believe to be F10 key) and exit setup. The system should restart, hopefully computer boot back into windows. If that doesn't work, Reset the BIOS to Default Values to see if that will make any difference.

Now, I booted my computer with the USB flash drive and repaired the windows problem. 

Thank you very very much! 

Glad to know computer is up and running again. Thanks for the update.

Good afternoon.  I read your reboot instruction regarding Legacy and UEFI.  Would these also work for a DELL Venue 11 PRO 7140? 

Just used your instructions and everything is working properly now. Thanks so much for helping the other guy.