Hi Susan and welcome to the forum. I moved your post to its own thread.
Can you give us the model and make of your trailer? And, is this problem just with DC?
In general, there is probably a fuse in line from the battery that could be blown. Your jack has its own fuse as well.
DW, 3 Kids and our Goldens
2012 Shamrock 233S
2008 Toyota Sequoia 5.7L 4WD