Hi patrickbishop,
First when saving some thing on a computer NEVER rely on one copy of your hard work, make backup copies and preferably save a copy to removable media.
Every time I go to make a major change to one of my layouts I save it as a separate map, ie Mylayout05, Mylayout06.
Now I will have a guess what happened to your map.
( OH! Before you do anything use Windows Explorer to open the Trainz UTC folder and copy your custom folder OUTSIDE of the UTC folder so you do have a backup copy of your work! )
(1) The last time you saved the map the file on your hard disk was corrupted and now windows is unable to load it, open Windows Explorer, right click on the icon of your hard drive, select properties, select tools and run error checking on your drive. You may be lucky and windows can repair the directory.
(2) The map was accidentally deleted from in UTC, in this case the deleted files does not show up in the recycle bin. There are utilities to recover files from the hard disk but they are not for inexperienced users and usually only work if you have not saved any new files to that hard drive since the file was lost.
(3) The map was accidentally deleted from windows Explorer/desktop in which case the files should be in your Recycle bin.
(4) Your copy Trainz UTC is corrupt and needs reinstalling. You did backup your Custom folder?
Sorry I have no idea if you can recover the map from a saved game?
I hope this helps,
Lindsay