You haven't mentioned what the Stop Code Error is. This would help.
Run the DELL Diagnostics.
As the computer boots, press the F12 key when the Dell logo is displayed. In the boot menu screen, use Up/Down arrow key to select the Diagnostics option and then press Enter.
This will tell you if the the boot disk is in working order or not.
If it is good then it is just a Windows problem - perhaps corrupted or missing files.
Here are some possible solutions:
UNMOUNTABLE BOOT VOLUME Windows 10 Blue Screen Error
To repair you will need a Windows 10 bootable USB drive. Burn a Windows 10 ISO file to an available USB drive using another computer. When done boot your computer from it. If you don’t know how to do it, please check How to Boot from a USB Drive, DVD or CD. Then you can try any of the methods listed below.)
1.) Fix UNMOUNTABLE_BOOT_VOLUME Windows 10 blue screen error with Automatic Repair
Using Automatic Repair is the easiest way to fix problem of this kind, if it works.
- a) On the Windows Setup screen, after you finish choosing your language; click on Repair your computer at the bottom left.
- b) Click on Troubleshoot on the next screen.
- c) Click on Start-up Repair on the Advanced options screen.
- d) Select Windows 10.
- e) The repair will be started immediately. Please wait patiently for the process to be finished.
2.) Fix UNMOUNTABLE_BOOT_VOLUME error by Fixing Master Boot Record
Master Boot Record (MBR) identifies where and how your operating system is located so that you can boot your computer normally. A malfunctioning MBR can cause problems such as UNMOUNTABLE_BOOT_VOLUME.
- a) Repeat the steps in method 1 until you see the screen of Advanced options.
- b) Select Command Prompt.
- c) Type “bootrec /fixboot“ in Command Prompt, and then press Enter. Repeat with “bootrec /rebuildbcd”
- d) Wait for completion of the process, and then restart your computer to see if the error message shows up.
3.)Fix UNMOUNTABLE BOOT VOLUME error using Chkdsk command
UNMOUNTABLE_BOOT_VOLUME error can be caused by problems on your hard drive. You can run Chkdsk command to check up and fix these problems.
- a) Open Command Prompt on your Windows 10 media as the steps above show.
- b) Type in “chkdsk /r c:“(Note that “c:” here refers to your boot drive and replace this with the letter you use in case your boot drive is not C Drive) and press Enter.
- c) Wait for completion of the process, and then restart your computer to see if it runs normally.