Large parts of the world turn into void

This is for minecraft pocket edition version 0.9.0--the pocket edition doesn't appear in the version drop down menu.
When I have died and respawned a couple of times the world turns to having mostly void. It is not really void--it is just that the blocks aren't displayed. I can still walk around without falling but it looks like there is nothing there. This device is new so I am still not sure how to check the system settings or take screenshots for you