Microsoft has recently released Visual Studio 2017 and you might be already started working in it. If you are using NuGet Package Manager Console, you may face an issue which prevents you to press the keyboard 'Enter' key.
If you faced this issue, which has been already logged, here is a workaround to resolve it for the time being while Microsoft is working on the fixes.
In case you faced this issue, as an workaround, restart Visual Studio 2017 and open NuGet Package Manager Console first before opening any project/solution. In some cases, deleting the 'project.lock.json' file and restoring it again also works.
Though Visual Studio 2017 has been recently released, Microsoft has already started working on the next features set to include in the new IDE. If you like, you can install the preview version of Visual Studio 2017 (v.Next) side-by-side to try out the changes ahead of general availability.