If you have the LM icon in your desktop, do right click on it and a bunch of options appear. There is one that shows you the location of the file (the LM folder). Click on it and the LM folder should appear.
Then, delete the "version" file and start the game as you normally do.
What deleting version txt does, is forcing an update, and therefore "downloading" all the files that are part of the game.
Hope this helps!