Can I undo a folder change in Windows 8 Live Mail?

I tried to transfer the contents of quite a large folder within Windows Live Mail (windows 8.1) into a new folder but nothing transferred and now only a very small percentage of the original folder is still there - any help would be greatly appreciated as this folder has over 5 years worth of essential email information. I do not have a recent enough back-up to use, can this action be undone? I know I can use system restore but I don't know if this would work or not and don't want to cause further problems by trying it. Thanks in advance.