I am the webmaster of the sunstar online shop, i am in charge all the things of the site, but i find i don't know how backup my site data, it is access and asp.net, could you tell me how to back the data?
Have you solved this problem yet? Sounds like you might need to talk to your webhosting company and ask them about the backup processes available to you. They will hopefully have some kind of in-house backup service that you can leverage.
There are many different providers for online data back. You can find them from Google itself. They will provide a backup for your website without any lose of data. And it is little bit costly but your data is secure.