I have never installed the DIVX player. I am more fmiliar with it as a library item, not an application. In other words, something another application such as Quicktime uses as a resource to play files with DIVX codecs.
Did you check if there is an uninstaller in the installer package? If there is then that is the best way to uninstall it. If there isn't then it is likely there are multiple components in different folders on your computer. You can try using Spotlight to remove DIVX components. It's an easy method but not always 100% effective.
It is very unlikely the DIVX installation corrupted Quicktime player directly, but it may have told the computer to use an incompatible DIVX component every time you try to play a certain kind of file.
Try playing some other kind of file such as a music file with Quicktime Player. If that is broken then you really may need to reinstall Quicktime. We would need to know more about which operating system version you use.