How to Upgrade Ubuntu 10.10 To Ubuntu 11.04 Natty Narwhal ?

1. Open the Update Manager application from the (System - Administration - Update manager ) menu., or open terminal by pressing Alt+F2 and type this command “update-manager -d”
2. In Update Manager screen you will see new distribution release (11.04) is available , Click on Upgrade button .In Update Manager .
   
   
   
   
   
3. Select the sub menu Updates from the Software Sources application.
4. Check the "Release upgrade - Show new distribution releases" drop down to make sure "Normal releases" is selected, and change it if otherwise. 
   
   
   
   
   
5. Close the Software Sources application and return to Update Manager.
6. In Update Manager, click the Check button to check for new updates.
7. If there are any updates to install, use the Install Updates button to install them, and press Check again after that is complete.
8. A message will appear informing you of the availability of the new release.
9. Click Upgrade.
10. Follow the on-screen instructions.