Can you confirm which version you are using (You have posted this in the old CrazyTalk Animator 1 forum).
It is always strongly advised to save your projects at regular intervals and always to a new file each time. Never overwrite a previous version of the project. This way, should a project become corrupt, you will always have a working version of the project available to drop back to.
Sadly if the file size is now 0 bytes, and you don't have a previous save, then this would indicate the project was not saved correctly and is now unusable. Although rare, corrupt files can occur in any software so precautions should always be taken to make sure you have backups or previous saves.