Use this article to check your power adapter and MagSafe port. Also try a different electrical outlet which is known to be good.
If the laptop is under warranty or still supported by Apple, then definitely take it to get serviced if the article I linked does not help.
If it is an older laptop: If the battery has become discharged it may keep the laptop from powering on. Sometimes disconnecting the battery and using the power adapter to turn on the laptop will work (may need another SMC reset). While the laptop is on, reconnect the battery and let it charge to at least 10% before powering the laptop off.