the american keyboards are lost

Hello, Strangely enough and for the first time in so many years, I cannot find anymore the american Keyboard. I use it regularly for the last twenty years for typing ancient Greek texts (much easier to find the all the accents, etc.). I can find all sorts of keyboards (Urdou, Uzbek…) except English and American keyboards. Is this related to the last Mavericks upgrade (X.9.4 on my MBAir). I am not sure how to recover it. Should I reinstall the whole system? Thanks in advance for any help.

That does seem odd. Just to be clear, you are going through "Input Sources" in the Keyboard Preference Pane? And when you hit the + sign below, you don't have "English" available, which should be sandwiched in between Dutch and Estonian?

Have you done anything like run a 3rd party tool to clear out international language support? You can try downloading and applying the 10.9.4 Update Combo to see if that resolves this.
OS X Mavericks 10.9.4 Update (Combo)

Thanks a lot! I downloaded the Combo update and it is o.k. I use a french swiss keyboard and switch to the american in which the location of every sign of ancient languages is known to me for a long time now.