Dell Inspiron 1525 message/boot up error

Hello,

I had my laptop on and it was working fine.  When I came back to my office I saw this message.  I did not download any new software, not running any new hardware/software, or on the internet.  How can I fix this issue?  Also, will I lose all of my photos, files, music, etc.?

I have no idea what this message means or why I received it.

Message:

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

UNMOUNTABLE_BOOT_VOLUME

If this is the first time you've seen this stop error screen, restart your computer.  If this screen appears again, follow these steps:

Check to make sure any new hardware or software is properly installed.  If this is a new installation, ask your hardware or software manufacturer for any windows updates you might need.

If problems continue, disable or remove any new installed hardware or software, disable BIOS memory options such as caching or shadowing.  If you need to use safe mode to remove or disable components, restart your computer, press F8 to select advanced startup options, and then select safe mode.

Technical information:

***STOP:  0x000000ED (0x86F4FE10, 0xC0000032, 0x00000000, 0x00000000)