Convert Japanese IME to English - after entry

After I enter data is in english, it is converted into japanese. I need a solution to reconvert the same data to english. Actually I will loose lot of personal information if I cannot reconvert. I found solutions where it was told that after changing the IME setting it won't happen again. I did that, but it does not reconvert the old data. Any suggestions on how to convert japananes keystrokes back to english