The reason it happened (i think) is because the vehicles expired. I.E, There are no diesel or Steam locomotives made after a certain point in time and the ones that existed went out of date.
There is a setting in advanced settings. See
Link <-
That and the console command works. Of course, you should never be completely out of vehicles... Especially at 2010.
You just have to build the right kind of track. You do this by holding the mouse button down on the track building icon. You can select normal track, electrified track, monorail and maglev. Each type becomes available as the first engine for that track is introduced.