Whenever I opened my Microsoft office word, or powerpt or any tool of ms office, this error says.. this modification is not allowed because the selection is locked.. and all I can do is print.. please help

Sounds to me like your trial version of Office has expired. When that happens, you lose the ability to create new documents or edit old ones, but you are allowed to still open and print the ones you've already made.

Time to purchase the final version or a full license key.