Well the title pretty much sums it up. my single player woulds aren't saving. is there any way i can manually save them? because it really aggravates me when i build things on my flat world then log off to take a break, only to come back to find ALL of my work gone. no mods installed, not even mcpatcher, completely clean version of minecraft downloaded, with my antivirus turned off when i download/update. there are no crash reports
I know this doesn't help, but I am having the same issue. I thought worked just fine for me last night, then today I logged on and almost died because the tunnel I was building was gone, but i was still standing where it was, so I was in the blocks. All of the items and tools i used for the tunnel was still used and gone, but anything I picked up was also gone. I still can't get anything i do to save. The only thing i see different about mine is that i am not in a flat world. I also know mine worked fine last time i played, then i updated it last night before i started playing. I want to guess that it's the update, but I dont know for sure.
(edit: oddly enough my inventory is being saved)