I am on well water. I have lots of horses and when the temperature outside is below zero I have to run the hose 24/7.
I have noticed that the water in the house & coming out of the hose has been less and less over the past few days. Today, there is nothing.
There is lots of water in these parts. Do it be a pressure problem or water problem or..
Maybe I shouldn't have let the hose run for so many days. Help, what can I do to have water again.

There may "be lots of water in th[o]se parts", but it sounds like you have pulled your well down to where the pump cannot keep up. The only thing you can do is wait until the water table comes back up and hope you didn't ruin your pump or more.

Running a hose 24/7 is REALLY wasteful, not to mention VERY hard on your well and equipment. If I can venture a suggestion, I would say that if you can afford to keep horses, you can afford to have a dedicated line correctly installed and provide a freeze proof waterer for your horses. Right now it sounds like you are coming close to inhumane treatment of the animals if the water system is not reliable.

I remember carrying hot water to animals when water froze, but we never just left a hose running, it would make the area around the watering trough a lake.

The hose runs into a ditch and in these parts that's all you can do, run the hose in freezing weather. Not full blast, just enough to keep the water from freezing. Is there some way of telling how high the water table is? In these parts, we are world famous for rain... it's unusual that temperatures are below zero but we've had some nasty weather spells lately.