My first guess would be that you have changed one of the built-in nodes and broken it. You can check for this by going to your workspace (If you don’t know where it is, open XOD and go to File > Change Workspace. It will show you path for your current workspace). Exit XOD and go into the __lib__ folder in your workspace and look for any folders that start with ‘xod’. Delete or rename the folders, then try running XOD and loading your patch again.
If that doesn’t resolve your issue, we will need to see your patch and the errors you are getting to be able to help.