John Deere 950 Hydraulics stopped working while sitting in the garage

[Dallas Nichols]

I have oil pressure coming from my pump up to the valve that distributes the oil to everything. If my pressure relief valve was stuck open, would it just push all fluid back to the transmission? I have no hydraulic function at all. I fixed my brakes, and went to move it again, and while on jack stands, it stopped working.
Any recommendations are welcomed. Im sure a fluid and filter change wouldnt hurt as well.