Yup, we need more details...
Is this tractor new to you ?
Is the lift lever locked up or down ?
There is a mechanism to lock the lift linkages in the lowest down position for when you need to remove the deck... see the height adjust knob, next to the lowest position is a lock symbol. The reason for this linkage lock position is because the tractor uses gas-charged lift assist cylinders for the deck lift... and if you remove deck without locking the linkage down, you have one h3ll of a time re-attaching things. Ask me how I know.
Pete