how to get the lookup field value back

Hi,

I am working on displaying a prompt message when a lookup field value is selected as '0'.

After the user responds to the prompt box, the lookup field has to display its old value instead of '0'.

How can I do this?

function abc()

{

var count=Xrm.Page.data.entity.attributes.get("new_count").getValue();

var countname=count[0].name;

if (countname==null){

return;

}

if(countname!=null && countname=="0")

{

alert("Please close the activity before making count as 0");

Xrm.Page.getAttribute("new_count").setValue(countname); 

}

}

Thanks