Had this happen once on our 1007. If it is the same step - two tabs run in a slot cut in either side of the bracket - then it was just a matter of getting the correct angle and a little bit of a nudge. IIRC, I held the step at about a 30 degree angle up. secured the left side tab at the front of the slot, then kind of rotated the back tab around and down until it snapped into the slot on the right a bit back from the front edge (maybe an inch or two). It take a very little bit of "English" to get it to snap in though. This was a couple to three years ago, so just going by memory...
2011 Jayco X19H (purchased 2015)
2008 Jayco 1007 PUP (purchased new, traded for the X19)
2018 Nissan Titan Midnight Ed.