Cannot open the block diagram of a previously saved vi

[amaglio]

I built a project and a VI under it yesterday, and saved them all. But today when i open the VI, I found the front panel became grey, and the bock diagram cannot open with "Ctr-E", or from the tag " window-> left and right". Does anybody know the causes.  Thanks a lot 

[RavensFan]

Could you have somehow saved it with the block diagram removed?

Perhaps it was a corrupted save.

You'll have to go to your source code backup system to retrieve an earlier copy.