I am not an experiences user in Adobe Photoshop. But some hours ago has happened the following thing Is not a valid Photoshop document. I got it at opening my working .psd file. I'm in trouble, I have to finish my work in 3 or 4 days, otherwise I will have the problems.
Do not use various methods like photoshop repair utility. I would suggest you something more interesting. I found this instrument, some days ago, just try it and if you want say your opinion – it is called Photoshop Online Service