Check your connection strings.
What works in development is generally a lot simpler than that in production: LOCALHOST or //MYCOMPUTERNAME as opposed to the name of the live site DB server - and dev setup generally work with windows authorization rather than "proper" login as well , which would be unusual for production kit.
Hopefully, you haven't hard coded them, and it's just a change to web.config...
Here is how I do it:
Supporting Development and Release web.config in ASP.NET[
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