solved my problem. The system is up and running kde 4.5.1
@Michael While downgrading it displays a conflict between few packages. The open to select is Y or I to install the packages from kde 4.5.1 and discard from from the version kde 4.5.3. Maybe running the above mentioned command asks you the same question again and you can then go ahead and select the correct option.
The command:
sudo ppa-purge ppa:kubuntu-ppa/ppa
solved my problem. The system is up and running kde 4.5.1
@Michael While downgrading it displays a conflict between few packages. The open to select is Y or I to install the packages from kde 4.5.1 and discard from from the version kde 4.5.3. Maybe running the above mentioned command asks you the same question again and you can then go ahead and select the correct option.