@codetonight,

You can restore the slices in doughnut chart to the old state by dynamically setting the exploded property of dataPoints to false as shown in the code snippet below.

for(var i = 0; i < chart.data[0].dataPoints.length; i++)
    chart.options.data[0].dataPoints[i].exploded =  false;

chart.render(); 

Kindly have a look at this JSFiddle for the working example on the same.

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Sachin Bisht
Team CanvasJS