You have 2 options
A . stay away from boot loader (0 Risk):
1- backup your SD data & All SD contents to your computer ( I Think it is not that hard)
2-Flash 4.2.2 with flash tool
3-Root on locked boot loader follow instructions here...
I like this one !
Dont worry ...
Download the Default Email app from Xperia Z ...
Xperia Z C6602 JB 4.3
thanks so much it worked
I appreciate your support :victory: