dolphin shows no preview and no search available

[Luca Ferrari]

Hi all,
after some apt-get commands I have my jubuntu 15.10 that do not shows
any more previews of files in dolphin and that does not allow me to
search with the find button: "Could not start process Unable to create
io-slave: klauncher said: Could not find the 'kf5/kio/filenamesearch'
plugin.."

I've tried to upgrade and dist-upgrade, but there is nothing to
upgrade and I cannot find any slave to solve the issue.
Any suggestion?

Thanks,
Luca