I can't log in to my Gmail account.
I've had a Gmail account for quite some time now, and have never had any problems logging in.
Yesterday, I typed in "gmail" into my Chrome browser (which I have done many times before) and was taken to the page that had he headline "Add Gmail to Your Google account." The box on the right says "Choose Your Gmail address," and if I enter the one I've been using, up pops "That username is taken. Try another."
Now, maybe my search skills are diminishing, but I can't find another page that will let me access my Gmail account.
What am I doing wrong, or what the heck is going on here?