finally after several trials and the inputs of different posts I could change back to the initial status:

devel-su
rootme

mv -f /usr/share/themes/base/meegotouch/call-ui/style/call-ui.css? /usr/share/themes/base/meegotouch/call-ui/style/call-ui.css.old

mv -f /usr/share/themes/base/meegotouch/call-ui/style/call-ui.css.orig? /usr/share/themes/base/meegotouch/call-ui/style/call-ui.css

close terminal and reboot

done

hope you can succeed too.