In a perfect world software works all the time…
So, you can stop laughing now. But if something gets really messed up there are a couple of options that you have to make it work again.
Often, one of the reasons for a hung instance of Zend Studio is a broken workspace. Zend Studio, and Eclipse, cache a LOT of information and the IDE is highly dependent on that information. Sometimes that information gets royally mangled. If the workspace is salvagable, and it usually is, the easiest way to fix the problem is to have Studio clean its cache.
First open up a command prompt (or terminal in Linux)
If all you need to do is re-cache everything all you need to do is go to your Zend Studio installation directory and type in ZendStudio.exe -clean
When you start up Studio it will re-cache all of the information that it had before. Usually this will work.
However, sometimes your system is just hosed and the current workspace is unusable. Studio will basically not start up because it is unable to load the workspace. Sometimes, though rare, this means that Studio will not start up at all. But fear not. The solution to this problem is to start Studio in a different workspace which can be done by using the -data switch.
The workspace that you specify does not even have to be an actual Studio workspace. It can just be an empty directory. That will usually be enough to get you up and running, at least minimally.