Yamaha xt 250 with no spark

I replaced the spark plug and now I can't even get it to start. It ran fine for about an hour, no problems other than no lights. I took it home and tried to start it up about an hour later and nothing. I can't even get it to kick over. I replaced the spark plug twice, replaced the inline fuel filter, cleaned the carb twice, cleaned the kill switch one the handle bars, cleaned the electrical contacts on all of the wiring on the bike, took off the coil, and other parts and cleaned the contacts on all the places that I could find on any wiring. I still can not get it to run. It ran GREAT for hours, started on the first two kicks and after it warmed up would idel on it's own. I don't understand what happened. If you think that you can help, I would be eternally grateful to you. The bike only has 2500 miles on it. Everything seems to be original on it. It even has the original tools under the seat. Thank You for your time. I replaced the spark plug and now I can't even get it to start. It ran fine for about an hour, no problems other than no lights. I took it home and tried to start it up about an hour later and nothing. I can't even get it to kick over. I replaced the spark plug twice, replaced the inline fuel filter, cleaned the carb twice, cleaned the kill switch one the handle bars, cleaned the electrical contacts on all of the wiring on the bike, took off the coil, and other parts and cleaned the contacts on all the places that I could find on any wiring. I still can not get it to run. It ran GREAT for hours, started on the first two kicks and after it warmed up would idel on it's own. I don't understand what happened. If you think that you can help, I would be eternally grateful to you. The bike only has 2500 miles on it. Everything seems to be original on it. It even has the original tools under the seat. Thank You for your time.