Site went blank, urgent please

Hi guys

My site http://www.strengthsbank.com suddenly went blank and some widgets disappeared. I spoke to my host and they said that there’s an error in the wp-includes in widgets.php line 591. When I asked for a restore they said that there’s something wrong with my theme and they can only restore it with a different theme., and that they did.

1. Line 591 of the reads
[code title=””]$this->widgets[$widget_class] = new $widget_class();[/code]

2. The lost widgets were both blank widget areas with some html inside them. Is there a way to get them back from somewhere?

What’s the issue. This is urgent because I’m going live soon after many delays.

Thanks