As the error message says "unmounted boot volume". In other words your boot drive has probably become corrupted.
Here are three possible fixes
***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 ***Startup 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.
***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.
***Fix UNMOUNTABLE BOOT VOLUME error by 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
There you are. Give it a try.