My lawn tractor clicks when I turn the switch but does not crank. This was sporatic at first but now it does it 100% of the time. I thought is was a bad solinoid, so I changed it out. Started once or twice and now we are back to clicks and no crank. Changed out the battery too. Dumb idea as now I have a louder click but no crank. Any ideas?

Did you check you heavy gauge (large wire) connections on both the battery and the solenoid you changed, remove and deposits and ensure they are tight. If these are good, verify your starter ground connection as well.
If all these check out, you may need to remove your starter and have it bench tested. (Do NOT hammer on it as some people like to do-this only guarantees you will have to replace it)

If you've replaced the solenoid, disconnect the positive (large red) cable from your starter and check for 12vdc at the end of this wire. If you have 12v here when turning the key, the issue is in the starter, as the previous tech mentioned. Briggs starters are particularly troublesome here... good luck.