How to fix The list cannot be Displayed in Datasheet View

By default, the Datasheet view of a list or library is not supported when you are using the 64-bit version of Microsoft Office 2010 installed on a 64-bit Windows operating system.

If your business needs require using the 64-bit version of Office 2010, you can install the 2007 Office System Driver: Data Connectivity Components to enable the Datasheet component. These components are available here on the Microsoft download center:
2007 Office System Driver: Data Connectivity Components

NOTE: If you are using a 64-bit version of an Internet browser, for example the 64-bit version of Microsoft Internet Explorer 8.0, there is no support for the Edit in Datasheet feature.

NOTE: You must install all 64-bit versions of Office products before you install the 2007 Office System Driver: Data Connectivity Components.

OTHER REASONS DATASHEET VIEW MIGHT NOT WORK
There might be other reasons why Datasheet view is not working, including the following:

• A datasheet component compatible with SharePoint 2010 is not installed.
• Your browser does not support ActiveX controls.
• Certain libraries and lists do not support Datasheet view, such as a slide library, and therefore the Datasheet view command is dimmed.