Blackberry Address Book Wireless Sync Option Disappeared or Disabled

To fix this problem: You need to reset “Desktop Sync Service book” using the following steps:

Go to Settings > Options > Advanced Options > Service Book
Select the Desktop [Sync] Service book from the menu, and select “Delete”
From the menu, select “Undelete” to restore the “Desktop [Sync]” service book
Settings > Options > Advanced Options > Enterprise Activation (Sometimes this step is not needed, check your contacts options)
From the menu, select “Activate” to re-try the wireless synchronization process
After Enterprise Activation process finishes check your settings for synchronization of your address book.

Address Book > Menu > Options
You will see that “Wireless Synchronization” has a “yes” value again (as it had disappeared before)

Warning:

Make sure you backup your pictures, videos, etc. This is going to delete all that.