How to turn Sleep mode back on

So, this is 100% my fault.   In an attempt to resolve a pronounced heavy static feedback sound issue I followed some suggestion that amounted to issuing some terminal command (I cannot recall what it was) that would prevent my computer from going into sleep mode due to lack of activity.   It was successful in keeping my laptop from going into sleep mode but did nothing to resolve the sound reverberation issue (I bought usb speaker as a work around).

What I would like to do now is re-enable automatic sleep mode again so my computer will enter sleep node when inactive again (point of clarity, I can manually enter sleep mode from the menu via System--->Suspend).

Hanging my head in shame,

The Scarlet Pimpernel