while updating i have lost contacts, photoes etc. how can i get it back?
next time do a backup of your data before an update, as updating will always wipe your device of any data.
how to back up: http://support.apple.com/kb/HT1766
did you use icloud at all for contacts? if so, make sure you are signed in settings>icloud and make sure contacts are on.
photos if you had them backed up on computer, just sync your phone with your computer.
Retrieving data ...