Unable to access the Windows drive in Ubuntu 14.04 [duplicate]

If you are using Windows 8 then fast-startup (aka fast-boot, and quick-boot) must be turned off. When you click "Shutdown" or "Restart" with fast-startup enabled the computer doesn't actually shutdown it just goes into a minimal deep hibernation state to make it look like Windows boots quickly. This means the Windows kernel is still partially in control of hardware even after you boot into another operating system. Under some circumstances this then causes problems such as mounting issues.

Steps:

In Windows 8 go to the Start Screen. [You can do this by clicking the bottom left corner of your screen.]
Right click on some empty space, and click "All Apps".
Click on "Control Panel". [You may need to search around for it.]
In the control panel choose "System And Security".
Click on "Change what the power buttons do". [It's a submenu.]
Uncheck the checkbox for "fast-startup", and click "save changes".
Shutdown the computer. [Use "Shutdown" not "Restart" just this once.]