Unmountable_Boot_Volume 0x000000ED

TECHINICAL INFORMATION 0x000000ED (0x823304E0,0xC0000006, 0x00000000, 0x00000000) I have windows xp and it was working fine until the next day What do I do?

This is an easy one. You need to run chkdsk /f c: Boot from your Windows XP CD and select "recovery mode" You will eventually get to a DOS like prompt

Type: chkdsk /f c:

wait for it to complete and you will be fine.

Alternatively, you can use Windows 7 or 8 bootable DVD or USB and select "repair computer" then "Command Prompt" then type: chkdsk /f c: