If you haven't followed the server status on these forums, you may have noticed that our server appears to be down if you're running Minecraft 1.7.x. Unfortunately, the client now speaks a sufficiently different protocol that it no longer reports the status of older servers. Rest assured, the server is still up, but if you haven't followed the instructions to downgrade from the new launcher, you won't be able to 1) see the service status and 2) connect. I've been paying particularly close attention to the server logs over the course of the past week or so, and it appears as though there are a large number of connection attempts (rather, probes) from newer clients that are not correctly showing the server status.
A wise man once said: Read the forums. This is where we post our updates and instructions. If you can't connect or you think the server is down and you're not periodically checking here, there isn't a whole lot we can do.
Alternatively, if you're uncomfortable with following the same version of Minecraft we do, you can log on to the TS server any time in the evenings, and one of us will walk you through the procedure. It isn't difficult, and sometimes all you need is a helping hand (and probably some updated screenshots in the linked thread wouldn't hurt either).