You should be able to access via FTP and check the files there, try re-upload your WordPress files, themes and plugins. Also you should remove the plugins you don't know very well. They might have an issue which is pushing your site down.
Shay, I'm not an IIS expert and I'm not a moderator of the forum either. You should create a new post on Forum with the title: How to enable errors in Web.config GoDaddy 500 Internal Server Error.
Someone who know about Windows IIS would help you. Also, you should put the content of your web.config on https://webconfigtransformationtester.apphb.com/ and check what's wrong.
Set tags as: iis, webconfig, godaddy, 500, error