So nuget.org is down...
Has your Microsoft dev shop gone on vacation because of the Nuget.org breakdown?
There are some quick fixes!
Add your local nuget cache as an alternative package source.
You probably want to use the same packages you’ve used before & these are hopefully still cached on your PC. Open the Package Manager Settings dialogue and add a new source:
%LocalAppData%\NuGet\Cache

****Or you can edit your **NuGet.Config** file located under C:\Users_[username]_\AppData\Roaming\NuGet as follows:
The config file won’t expand environment variables so you’ll have to hard code the location of your nuget cache.
Host your own NuGet feed
You can setup your own NuGet feed, mirroring packages that you regularly need. See http://docs.nuget.org/docs/creating-packages/hosting-your-own-nuget-feeds
Use a 3rd party to host a NuGet feed for you
I haven’t tried this yet but it’s something I plan on having a look at in case, heaven forbid, NuGet goes down again!
Add the local package source to your NuGet.config
Have you enabled NuGet Package Restore on your solution?
Open the.nuget/nuget.configsolution file and add the following element:
****UPDATE: This doesn’t actually work as you expect, unless nuget.config is in the current working directory. Please vote for this work item to have it work as expected.