We can't know anything. We know nothing about your version of AE, what preset you use, what font etc.. Many text presets use specific expressions and you may have inadvertently keyframed something there. Otherwise we realyl need al lthat info and a screenshot will also help to clear up things.
And if English isn't your first language, please feel free to type in your native language, and let us use the translator.
But if English IS your first language, you are in desperate need of remedial lessons, because your problem as written is totally incomprehensible.