Look in a cabinet or near where the 12v fuse box is for a battery disconnect switch. Sounds like yours is off. Those are used to keep the batteries from running down when the trailer is stored.
Barney
2004 Sunnybrook Titan 30FKS TT
Hensley "Arrow" 1400# hitch (Sold)
Not towing now.
Former tow vehicles were 2016 Ram 2500 CTD, 2002 Ford F250, 7.3 PSD, 1997 Ram 2500 5.9 gas engine