How about few more details about your tractor, its age, post some pictures of your battery and its cables, the starter and of the overall tractor.
Sometimes it is as basic as Dr Honda has suggested. Other times it is very simple and easily overlooked details.
A short story to illustrate my point.
Recently there was an owner of a tractor with many of the same symptoms as your tractor. Cables were cleaned as well as the battery terminals.
I asked the owner to check where the ground cable connected to the engine block. He felt it was good and tight but to amuse me he loosened the bolt securing the ground to the engine. What he found was a very well painted engine block with the ground cable tightly bolted against the paint.
The bolt threads were providing a ground for some time but with rust and time, they no longer could pass the starter current.
A bit of scrapping off of the factory paint and it is like a new tractor again.
There are many tests you could do with a $10 multi meter if you are so inclined and the instructions can be provided. For many owners, they just want the problem fixed regardless of the cost.
If your battery is 5 years old then it owes you no favors and replacing it is worthwhile even if it is not the cause of your issues this time, it soon will be.
Dave M7040