modification not allowed because selection is locked..whats this?

[ging]

I typed and saved a document in microsoft word, then when i open it to make
some changes, everytime I type a word the cursor doesnt move at all, hence i
could not make any changes.. and everytime I press any key theres this
message saying "modification is not allowed because the selection is locked"
what does it mean? how can i resolve my problem. i could not use microsoft
word anymore.

 

[Suzanne S. Barnhill]

Either you have not activated Word, or it is a trial version that has
expired.