i cant update my os.
and my software release is not available.
why it is showing not available.
i cant download whatsapp now bcoz my os is not updated.
my current version is 10.0.10.261.
but other bb users have 10.0.10.648.
plz help me.

Blackberry has not posted at least openly the OS for the Z10. They do indicate that the "link" app which replaces DM does it. Which code level or rev is even harder to find.
If you dont have "link" try downloading and see if it helps.

this is for the Canada version but others are listed.

BlackBerry Link - BlackBerry 10 Smartphone to Computer Sync - Canada