Well, as it stands, there are two things that could be wrong. One, the internet connection is not strong enough, try moving closer to modem, checking the firewall, making sure the game isn't being blocked. Also try running game as admin, I doubt this would do anything, seeing as you were able to play before.
Secondly a simple reinstall would not require you to redownload or alter your created content. Simply uninstall the game, and then find the saved download setup and reinstall it. Should supposedly fix problem.