Requirements 101: Have an automated deployment
If you don't have an automated deployment, it generally means that you are in a bad position. By automated, I mean that you should be able to push a new version out by double clicking something. If you can't get automated deployment script in under an hour, you most certainly have a problem.
Sometimes, the problem is with the process, you don't have the facilities to do an automated deployment because parts of the deployment is sitting in people's head (oh, you need to configure IIS to use Xyz with the new version), in other cases, it isn't there simply because people haven't tried.
Yet, automated deployment is one of those things that you can create in isolation, without getting commitment or support from the rest of the team. This is usually the first thing that I do in any project with existing codebase that I come to.
It is also a good way of taking care of problems in the process. If you have a hard time deploying because you database change management process is broken, you need to fix that before you can get an automatic deployment ready.
Also, notice that I am explicitly talking about automated deployment, not about having a build script. One of the requirements for automated deployment is a build script, but that is just one of them.
I don't care that you can or can't build the software, I care that you can deploy this successfully. And yes, this include doing things like deploying to several machines, stopping and starting services, updating the database schema and applying any data migration processes, and even doing rolling update, if this is a requirement.
And I'll leave you with just one final thought: Prayer should not be part of the steps in the deployment process.