What to do if I recieve a notice to vacate for non payment but paid my rent and no one is at the rental office?

I paid my rent on time and a few days ago, I recieved a notice to vacate my apartment on the 12th, which a Sunday. Now, when I went up to the office to talk to them about it, there is and has been all week long a sign on the door saying "Gone to training". Now there were a couple of people with the same situation that showed of in front of the office like I did. I can't call and leave a message cause they're (the apartment office) voice mailbox is full and just goes back to the recorded message when it comes down for the beep. My rent check has not been cashed yet. I did drop it off at the night drop off box like so many others did also. And it's not just me, but quite a few other tenants in my complex is in the same situation. I don't know what to do. I'm worried to put a stop payment on my check because of the obvious, but my rent check is somewhere just floating around and I'm being forced out of my home. Any ideas would be a big help. Thanks! By the way, I live in Dallas, TX