I had the same issue recently. At work, most use is through a terminal server. Not sure if Adobe was updated, or changec, because I never paid attention to the version before. Currently it is Adobe Acrobat Standard 7.0. I'm not sure if there are any other numbers to that designation as I cannot find a simple "About Adobe" under help.
In either event, there's no more typewriter under tools. However, it looks like I found an alternative.
Tools > Advanced Editing > TouchUp Text Tool
However, I am noticing it is not as versitile as Typwriter was. For example, I am trying to add numbers in a "Field" on a form, but when I click the document with the tool where I want it, it won't allow me to type where I want. I have to put the text "next" to the field title, and not under the title where you would naturally complete the field. If that makes sense.