I was changing the theme. Aftert that the device is hungs. I try to reboot the device and it stop at the boot up screen (with a white backfround and hour glass keep turning).

I did remove the battery and replace it. The situation still the same. Any expert here can help me to resolve it? what is the cause? Is it virus attack?

Thank you in advance

It is not a virus attack.
It was a problem with the theme.

Wipe the device and reload it. Use a different theme.

Try this:

1. Uninstall any BlackBerry software you have (except Desktop Manager 4.2 SP1 if it's installed).
2. Install Desktop Manager 4.2 SP1. (The link isn't working at the moment, but it should work soon! The info page is here.)
3. Install your OS. Find it here.
4. Run Desktop Manager. When it connects, run Application Manager and reinstall your OS.

If that doesn't do it, you'll need to completely wipe your device using JL_Cmder, and repeat the steps above.