I was using it since it's first release. But yesterday after I download the new update, it erased all my desktop widgets including Foreca, Personal Data Plan and Personal Picture Frame. I tried re-downloading but same problem. Now it doesn't show on the screen eventhough I can see it in downloaded folder.

Ates, it's a known problem that hildon-home may restart in a safe mode (with 3rd party widgets disabled) during widget's installation (https://bugs.maemo.org/show_bug.cgi?id=8895). If it happened, add your widgets back to the desktop via the desktop menu.