If it was a CDP:
Go to Content Manager, lookup all the material you installed on the day you installed that CDP and set a filter to "locally modified = true".
Exclude your own material from that list.
If you did not install anything else that day or modify anything, you now have a list of the material you installed and can delete that.
If not, you have to do some gambling and hope you also have the other CDP's you installed that day.