I used 11.4 including KDE Kontact and saved almost all data to an external disk and made a System backup but forgot to save the Data from my “Kontakt” account. Due to installation problems with update to 13.1 I have chosen new installation. When it came to partitioning I selected LVM-based ext4. I believe before it was also LVM-based and I am sure it was ext4.
Do I have a chance to get the former “Kontact” data like emails, notes and calender-events back?
Hi, welcome
If you reformatted, no way. If you have a copy of your entire /home/YOURUSERNAME (not sure about the KDE version, depending on that even /home/YOURUSERNAME/.kde4 may be enough), yes, you could reuse that, Kontact then migrates the old stuff to newer where needed.
One thing you missed, is the “Import Partitioning” in the installer. It would have imported the present partitioning, suggesting a reformat of only the system volumes, i.e. “/”. In such a case it still depends whether /home was on another partition. If yes, the installer would have left /home untouched, allowing you to reuse it on the next openSUSE version. If no, I suggest you make that step now, it will make things a lot easier on future installs.