Briggs engine? When you turn the key to start, can you see the screen atop the engine attempt to turn/rotate any at all?
If you see the screen try to turn, then you likely need to adjust the engine valves.
Adjusting the valves on Briggs OHV engines is required periodically to maintain the correct compression release performance, which in turn is vital to achieving starter action.
But if you hear the starter solenoid click with no movement of the screen at all, you may have a battery cable or starter cable issue.

Try jumping across the 2 large studs on the starter solenoid to see if it cranks.
If it does, starter solenoid or it's 2 connections are bad.
IF not, let us know.

You may have replaced the battery, but are you sure it's fully charged? Load tested?
On another forum, a guy bought a new battery and finally, after a couple dozen posts, he FINALLY had it load tested.
Bad cell.

Thanks Bill I jump the studs on the starter solenoid and it started right up. I purchased a new solenoid and installed it the tractor started right up. again I want to thank you very much......

Thanks for the follow up.
Mownies advice is also good.
Valve adjustment IS a normal (but underlooked) maintenance item.
Often, we see complaints about slow cranking.AFTER they've needlessly replaced the battery, solenoid........etc.