Save Corrupted, "Value Cannot be null"

[kspChad]

Opened my game today and my main save can't be accessed. All i see is, "Error Accessing this save." "Value cannot be null."

What do i do? How do i load a backup?

[Curveball Anders]

Inside your saves directory  there's a backup folder,

As in KSP/saves/yoursavename/backups/persistant(timedate).sfs

Copy that to KSP/saves/yoursave/persistant.sfs

But your mileage my vary, I don't believe in any games stock backup, my startup script does backup for me ...

Edit:
Info from Elders:
You don't need to rename it to persistent.sfs.  You can manually load the backup from the load menu

 

[kspChad]

I tried what you said and there was no difference... any other recommendation?

[kspChad]

But what is the load menu?

[kspChad]

And if i cant get it back at all, the backup still has all the saved planes files. Can those be salvaged?