Hi. I know this is an old thread but I just wanted to let others know how I got past this problem, as the answers above don't directly say what to do :-(
As it's been posted up there, it was suggested that google+ has to be activated and that should fix it. But Axe's reply doesn't say Yes It Worked, it only says that that was assumed to be the problem. Actually the whole story don't make sense because if the original poster says he disables google+ anyway as it's a battery drain, then that would mean he's never had camera or gallery working - both features and everything connected with them (handling photos and video etc.) all vanish. Well it all confused me a bit anyhow lol
Well, i went through the motions, clearing up various caches by various methods, checking for updates etc etc.(i cant recall all that I did as there was so much to try), but the bit that did fix it was....
I downloaded the appropriate version of the GAPPS app (google apps). Its a big file, over 140Mb for my Y300 mobile, and I reflashed that through CM recovery mode (my phones rooted and upgraded to what Huawei should have created in the first place ;-)
That didn't actually fix it though yet. I then found that there was no Google+ app around to be checked, but I did find that the Camera app was there (still no links anywhere on the phone to either Gallery or Camera, and using any app that tries to access either just made it fail and give a Stopped Responding error).
To get the links back as normal, I went into Setting > Apps > Camera and even after reflashing the full GAPPS package, that was left disabled lol. Weird !
I Enabled that and yippeeee - that was it, everything just works again now.
On another point mentioned earlier, thumbnail views of photos taken previously where only being shown as grey boxes - even if the files where perfect even a few hours ago :-( The bad news there seems to be that they are corrputed beyond repair if that happens, and yep it can happen at any time. I lost 12 photos out of 108, and the only thing they had in common was they were on the same memory card in the phone, nothing had been changed, no crashes, no new apps, no editing, they just went grey. Some went grey when I happened to be looking for them, and some others went grey after I'd used the standard video recording app - it froze for a minute when the recording was ended, and left a grey file with all the right length/date/time, even extra details like Camera Model.
No recovery/repair software seems able to repair them, and it also happens to video in the same way.
For now, I've backed up all files, fixed the camera/gallery as mentioned above, and then Low Level formatted my SD card. Lets see how long this lasts then 
Good luck to everybody who has this kind of frustrating problem.
