"Cannot open the file"

Hi.

I was working with CS6 when I exported a file to pdf and saved it later this morning. Now I'm trying to open it but I recieve the next message:

"Cannot open the file xxxx.indd. Adobe InDesign may not support the file format, a plug-in that supports the file format may be missing, or the file may be open in another application."

Also, the file seems to be like 5 GB of weight or so.

Anyone has any solution? I've checked a few posts of this discussion forum about the same message but none of them was helpful for my case.

Thanks in advance and excuse my English.