A few days ago, a problem arrived in the server world, region file 0_0.mcr aka land area -512X / -512 Y had become corrupted and several chunks in the region file were destroyed. We do not know how this had happened, but sadly had erased several parts of the world in it, such as buildings, homes, castles and etc. Most of which has since been replaced via our database of server movements, and most other missing bits will be replaced in time.
As for an actual back-up, sadly there is none. This had happened DURING the server backup, so we were unable to find a working solution other than our database logs. Everyone who was affected will get Creative mode temporarily in the event their structure is not fixable.
This region was the only region effected. This hopefully will never happen again.