I installed VS2015 Update 2 and now nuget package manager does not find any packages outside of the \"Microsoft and .net\" package source. It looks like the nuget package so
The nuget.org package source is still there after the upgrade for me. But if it ever disappears you can add it back as:
Name: nuget.org Source: https://api.nuget.org/v3/index.json
Name: nuget.org
Source: https://api.nuget.org/v3/index.json