I've been using Defraggler for some time now and have found it to be a great reliable program. Last night I started a defrag on all three partitions of my single physical HDD. I awoke to find the defrag "complete" and only two of the partitions listed. After a reboot, things are the same. Windows Disk Management sees the missing partition as Free Space, and only gives me the option to create a new blank partition.
I have managed to restore the deleted partition using MiniTool Partition Recovery. I don't know if the MBR was corrupt but all the data on the disk is fine and there are no bad sectors after a scan. Are there any logs I can provide you with for a bug report?
I lost all partitions on a GPT disk and Minitool Partition Recovery is not suitable for GPT discs.
Lucky indeed! I had a bit if a general clean up yesterday, including un-installing lots of stuff and running ccleaner, but I rebooted and used the computer for a few hours before running defraggler so I am fairly certain the other actions were not the culprit. Again, if you require further information or log files for a bug report, please let me know.