.net – ‘Microsoft.ACE.OLEDB.12.0’ provider is not registered on the local machine

I'm trying to get data from an Excel file on a button click event. My connection string is:

 string connString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\\source\\SiteCore65\\Individual-Data.xls;Extended Properties=Excel 8.0;";

When I click on the button, I got the following error:

The 'Microsoft.ACE.OLEDB.12.0' provider is not registered on the local machine.

I have no clue how to fix this. My operating system is Windows 7.