Visual Studio 2015 Build and Run Keyboard Shortcut

By default, when you press CTRL+F5 Visual Studio asks you if you want to build a changed project:

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It looks like you selected Do not show this dialog again and pressed No.

To revert it, change HKEY_CURRENT_USER\Software\Microsoft\VisualStudio\14.0\General\BuildOutOfDateProjects from 1 to 2.

For all possible values see __BUILDOUTOFDATEPROJECTS Enumeration.

Update (thanks to Cody Gray): Instead of editing registry, check the On Run, when projects are out of date option:

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