I'm working in an environment where the developers work directly with script and image files on the live deployment web server. This is scary and has caused a few, though so far surprisingly few, issues. Source control is not used at all for these changes, the changes are made on the live server and only on the live server. I don't know how to make it so that changes other developers have made on the live web server are kept/merged when I deploy my changes to the live web server. This issue would seem to make matters worse using source control rather than better.
I have personally setup git and svn servers, and used version control with git and svn for the past several years on many desktop app and mobile app projects. But this has me stumped.