Text disappears suddenly in office table

[anano]

hello well I have win xp operation system and office 2007 on it. Yesterday I create a table in office 2007 and add text in this table saved it and close. today when i opened my document and add a new textin table suddenly my added text dissapeared and make no visible. please help me every time i added text in colums this text suddenly dissapears maybe some options must be cheked in office options???? pleaseeee