After upgraded my ipad 2 I lost all my pictures and videos

That message indicates to me that the iPad is being recognised as a camera and that the 'windows camera wizard' is opening and is not finding any photos or videos on your iPad - is that what you are seeing ?

If you no longer have iTunes installed on your computer then you can redownload it from here : http://www.apple.com/itunes/download/

Depending upon what's been done to/on your computer, then deleting and reinstalling iTunes shouldn't delete any backups that are stored on it - unless, for example, you've updated or reinstalled the operating system on your computer.

If you reinstall iTunes then it should automatically pick up any backups that are still on your computer - if you go into Edit > Preferences on it (iTunes > Preferences on a Mac) then the Devices tab on it (as on Diavonex's screenshot) should list your backups.

If you go into Edit > Preferences (if the drop-down menus aren't showing then control-B should get them to show) and select the Devices tab then are any devices/backups listed e.g. from http://support.apple.com/kb/HT4079 :

If not then if use windows explorer then can you see if any backups are stored under :

• Mac: ~/Library/Application Support/MobileSync/Backup/
  The "~" represents your Home folder. If you don't see Library in your home folder, hold Option and click the Go menu.
• Windows XP: \Documents and Settings\(username)\Application Data\Apple Computer\MobileSync\Backup\
  To quickly access the Application Data folder, click Start, and choose Run. Type %appdata% and click OK.
• Windows Vista, Windows 7, and Windows 8: \Users\(username)\AppData\Roaming\Apple Computer\MobileSync\Backup\
  To quickly access the AppData folder, click Start. In the search bar, type %appdata% and press Return.

It sounds like you've overwritten any backup that might have had the photos and videos in it with a new backup - in which case they are lost. You hadn't also been backing up to the cloud directly on your iPad (Settings > iCloud) ? If not then you won't be able to get them back