my Time Machine (TM) light was off.
Perhaps you mean to say Time Capsule here?
(Time Machine is software on your Mac that is used to backup the data on your Mac to another hard drive.....like a Time Capsule).
If you have a Time Capsule, disconnect the power cord for a few minutes, then connect it again to see if the Time Capsule will power back up.
If the light on the Time Capsule still will not function, unfortunately there has likely been a failure in the internal power supply of the Time Capsule.
Contact Apple Support to discuss your options.
http://support.apple.com/kb/HE57
Apple will not offer repairs if the Time Capsule is not covered by warranty or AppleCare, but it might be possible to repair the Time Capsule using the information in this link:
https://sites.google.com/site/lapastenague/a-deconstruction-of-routers-and-modem s