I have made a Facebook application (using C# and ASP.NET + SQL server), which is hosted on my localhost. Is there any other place where I can deploy this web application, so that it can be accessible from anywhere on the internet.
What changes should be made in the connection string, while deploying this on the internet???
Shop around for some web .Net hosting.
Looking for free web hosting of your .Net app? Try monoforge. It's very unlikely to find free web hosting for Microsoft based products. It costs money. So, my advice is to try to retrofit your app to Mono and have it hosted on MonoForge.
You will need a web server/host supporting ASP.NET and SQL server. There are a plenty of options available.