Aug 26, 2014 03:27 AM|Starain chen - MSFT|LINK
After modify the code as PawanPal said that, please check whether the specific record is deleted form the database. You could connect to the database to check it directly or you may refresh the current page if the current page load that data.
For your code, you don’t bind the data to the grid after delete the record in the GridView1_RowDeleting method. So it won’t show anything.
For the other issue, you should to check whether the textboxUN, textboxEmail, textboxPwd and ddllist aren’t null.