Windows will not start due to error message

Hello, I am getting an error when I start my computer:

A problem has been detected and windows has been shut down to prevent damage to your computer.

UNMOUNTABLE_BOOT_VOLUME

Then gives me ways of getting it to start up but non of those have worked.

It ends with the following:


Technical information: *** stop : 0x000000ED (0x86795900, 0xc0000006, 0x00000000, 0x00000000)

Please help with any ideas:(

Deb