I have upgraded my Xcode to Xcode 5. From where can I change the version and build number which are now not visible in Target Summary?
In the screenshot you posted your target is a library, which do not have the build/version number.
Select your target and then go to the General tab.
Then Identity you can change the Version ad the build
Or open the Info tab and then Custom iOS Target Properties, here your can change the build and version number.