root device install again I want to root my s4 phone I have some apps on it which are no longer are availeble for download, do I have to reinstall them (in other words some programs are lost)

Hans
If you just root your phone and do not flash a custom rom you won't need to reinstall all those apps.

If you are planning to flash a custom rom you will need to backup all those apps. For backing up system app i use es file explorer to go to root> system folder then to apps you will see all the system apps installed in your device copy those apps in your sd card and after you flash your rom you can reinstall those apps . No need to download those apps