Permanently change the ‘view x items per page’ in the admin backend from the default of 20

In sections like CMS->Static Blocks, CMS->Pages, Catalog->Manage Product etc.  if you have more than 20 items magento will split them into multiple pages of results.

The fix itself is pretty easy, just open up:

app/code/core/Mage/Adminhtml/Block/Widget/Grid.php




Somewhere near the top of the file (around line 70) you'll find the following code:

protected $_defaultLimit    = 20;

Replace it with: 

protected $_defaultLimit    = 999;

As your updating a core file within Magento this change will be overwritten every time you upgrade your magento so you'll have to go back and alter it again after each upgrade. 

If you want to add new page no to pager than open file 

app\design\adminhtml\default\default\template\widget\grid.phtml




Somewhere in the file (around line 81) you'll find the select tag code and copy option line and paste with your desire page no.