Is there anyway to replace my lock button on my iPod?

elizabeth I recognize this is an old question but just for completion sake, here is what should have happened. The lock switch is soldered to the bottom of the logic board. There is a plastic slider that moves the switch. Check that the slider is properly seated and moves the switch. If it does not move, you would need to replace the switch by de-soldering the old one and replacing it with a suitable new one. Since they are/were not readily available, you would need to find a donor board to get a switch. Use something like this guide Sostituzione batteria iPod Nano 3a generazione and Step 7 shows the switch and slider.