Blowing that photo up a might, it looks to me like the nut is further down the slot that it used to be, and depending on the motion of the gear shift, it would make sense that the linkage is now too long, especially if the shift pattern is a standard PRNDL, then if it were suddenly too long, you would have to move it down a notch or two to get into the gear above the shown position.
In other words, Neutral would now be Reverse, Reverse would now be Park, and the first D position probably is Neutral and you can't get all the way down to the low range.
If the linkage were suddenly too short, then you would not be able to get it into park, it would show Park next to the shift lever, but would actually be in reverse.
But then I could be all wrong, wouldn't be the first time this second............
Put it up on 4 solid jack stands or a lift, have someone get in it and move it through the gear selection while you watch the linkage, should give you a clue, then do what Harley suggested, disconnect the linkage, shift it by hand (with the engine at idle and all four wheels well off the ground, stay away from the spinning drive shaft!) and if you can move it to all positions, then shut off the engine, adjust the linkage, and try it again with the gear shifter inside the cab and the wheels off the ground.
Works, then road test it!