I was trying to change my Hud settings and I must of altered the Reverser settings. Now I can't press the up arrow key on the reverser to put the train into forward. Same if I have to switch stuff on like the aws and other safety systems. I'm using a Steamdeck not a keyboard. It first happened while I was driving an Azuma but tried on a class 150 and although could put it into forward I got to one of the stops and it just stopped working.
I'm not familiar with the steamdeck, but if it's buttons works like a controller normally there's no way to reassign these buttons, even accidently. (If someone says that's not true, I would like to know how to do it...) The keyboard keys can be reassigned, so have a look in the settings/controls/mouse and keyboard menu and give it a try. Search for the arrow up key and try to reprogram this with your up arrow button. Perhaps it works. If not I would try to re-install TSW.
Did you change from the Immersion control scheme to the Classic one? The Classic control scheme has the reverser mapped to the left analogue stick, a remnant of the control scheme from Train Simulator.
I've just checked the settings and it was set to immersive I changed it to classic but made no difference, so changed it back to Immersive. Now I can't use the A button to switch on headlights or any of the operations that require me to use use the A button. I think I'm going to have to uninstall the game and reinstall it. Everytime it messed up like this I always have to uninstall and reinstall it, it's getting really tiresome having to do this. Why can't Dovetail Games make it Steamdeck compatible after all the price they charge for dlcs surely Dovetail can buy a Steamdeck to test it on. It can't be all that hard as they make a version of TSW4 for Xbox and PS5. P.S. Sorry for the rant.