Why has my iPhone deleted photos?

My iPhone is only showing 143 photos in my photo stream now, when beforehand it has shown all 991 that are showing on my iPad in the same photo stream. I don't understand why this has suddenly happened and would like to be able to get the photos back if possible… Does anyone know how to do this? I'd prefer not to create a new photo stream and transfer them all into that from the iPad but if needs be I will.

Call Apple, a similar thing happened with me and they walked me through it step by step. This may have been caused if you recently plugged your phone into a different computer.