Solution
If you have access to a PC with the same version of LabVIEW installed, you can simply copy the examples from the "unmodified" LabVIEW installation and overwrite the "modified" examples on your PC.
If you don't have access to a PC with the same version of LabVIEW installed, then you need to repair the LabVIEW installation to restore the LabVIEW examples to their original versions. Please follow the steps in the following article to repair LabVIEW:
Repair Software In NI Package Manager (NIPM).
Please take into account that if a specific example that you want to restore gets installed with an NI driver, then you need to repair that specific driver and not the LabVIEW installation.