<p>When I launch perfmon and try to add a counter, the displayed performance objects are all numbers. How can I reset these Performance objects?</p>

What do you mean my "reset"? What's the behavior you're expecting?
The perfmon "System Monitor" view shows the (near) real time value of the counter. Since these measurements are always being taken there will (almost) always be a number there.
If you want to be able to control the collection of these measurements, you need to create a Counter Log. Additionally, you can use the logman command to manage the log from the command line or a script.