Can´t see my projects after close it in MAC ..my sequence does not show my clips, audio, images..etc

I have work on my project adding clips, images, audio files into a sequence, however, after saving the project and close it, when I reopen it, the project does not show any clips, audio, transitions, etc in the timeline. I am able to see the sequence name, but nothing else.

I really appreciate your help because is happening frequently.

Thanks a lot

José