Not real familiar with your machine. You have a rear and mid pto correct? I would bet or hope you bumped one or the other. You also need to have the hts in neutral I believe. If it's none of that, check the seat safety switch and report back. Good luck.
There are probably several safety switches. Seat, PTO (both), at least.
By the way, on another important topic, you have used your email address as a username. Bad idea, unless you like being buried in spam. Any time you post your email address in public like that yous are going to get picked up by spam bots, and then the fun begins.
I suggest you contact an administrator and ask them to change your username.