I had the same problem with my Huawei Asscend G7. That happend to me about month and a half ago and as I didn't know what to do, I restarted my phone to the factory settings. That solved an issue, although I lost all my messages, my Viber messages and photos I got from Viber. Everything was fine until today when I found this conversation. I cleaned up catch as paulwelford1 said and now is working, but will see for how long.
This is a very bad issue for this phone, as everything else works fine.