var style_ary =
[
"layer1",
"layer2","layer3","layer4","layer5","layer6","layer7","layer8","layer9",
"layer10","layer11","layer12","layer13","layer14","layer15","layer16","layer17",
"layer18","layer19","layer20","layer21","layer22","layer23","layer24","layer25",
"layer26","layer27","layer28","layer29","layer30","layer31",
"layer1"
];


function widgetOnLoad()
{

var style = GetValue("style","layer1");
eval(style).Visible = true;

}

function changeStyle(Sender)
{
layer1.visible = false;
layer2.visible = false;
layer3.visible = false;
layer4.visible = false;
layer5.visible = false;
layer6.visible = false;
layer7.visible = false;
layer8.visible = false;
layer9.visible = false;
layer10.visible = false;
layer11.visible = false;
layer12.visible = false;
layer13.visible = false;
layer14.visible = false;
layer15.visible = false;
layer16.visible = false;
layer17.visible = false;
layer18.visible = false;
layer19.visible = false;
layer20.visible = false;
layer21.visible = false;
layer22.visible = false;
layer23.visible = false;
layer24.visible = false;
layer25.visible = false;
layer26.visible = false;
layer27.visible = false;
layer28.visible = false;
layer29.visible = false;
layer30.visible = false;
layer31.visible = false;


var style = style_ary[Sender.tag];
eval(style).Visible = true;
Setvalue("style",style);
SaveIni();
}

all the things are working fine
just you forget to add widgetOnLoad in widget's Onload event