when we use earthquake or nuclear type weapon,if a crate falls but not sink,then the game gets frozen. any idea how to fix that bug ?

Oh, like if you have water drops on, but the crate hits the bottom? This was a known issue in Worms Armageddon, and I believe it was fixed in one of the updates (though I'm at work right now and can't verify that I'm right here). There are no updates planned for Worms World Party, so if you want bug-fixes and new features, I suggest you switch to Worms Armageddon.

exactly..too bad then if there's no update ,cause it really wastes the game

Or you could wait till WA and WWP are combined...

That, or you could switch to WA as I suggested and have all the updates as they are released. ;)