Your Google talk might have upgraded to Hangouts, but most users feel its annoying and dont serve the purpose of normal chat application.
Many people desperately wants to switch back to old Google talk app. Here is how to get it back.
1. Go to settings and open Apps.
2. You will see Hangouts under downloaded Apps. Click on that.
3. Click on Uninstall updates.
4. This will uninstall Hangouts and bring back Google talk again.