I had been using iCloud email on a Dell Chromebook but suddenly today it will not let me log in. Any ideas?

Hey TomTerrific1955,

Thanks for using Apple Support Communities. To help, we'll need a bit more information on what happens when you try to sign in. Does an alert appear, and if so, what does it say? In the meantime, this resource has great steps when you're having an issue signing in to iCloud that could help: If you can't connect or sign in to iCloud - Apple Support

Another step that can help with odd issues is to restart your computer. Give that a try if the steps above don't help, and let us know if that makes a difference.

Keep us posted.

Take care!