modal PopUp Window in ASP.net Problem

user clicked on edit or delete button in Grid View need to fire the modal window
You need to inject JavaScript at row level of the grid. You would need to use RowDataBound event of grid that triggers on every row bind. In this, inject JS code to open the modalpopup on click of a control.
Sample:

//For injecting JS, you need to use RowDataBound of GridView, something like:
protected void GridView_RowDataBound(Object sender, GridViewRowEventArgs e)
{ 
   DataControlRowType rtype = e.Row.RowType;  
   if (rtype == DataControlRowType.DataRow)  
   { 
      // Control specific
      LinkButton l = (LinkButton)e.Row.FindControl("LinkButton1");
      l.Attributes.Add("onclick", "javascript: OpenModalDialogMethodDefinedInJS();"); 
   }
}

Refer: Using JavaScript with ASP.Net GridView Control[^]