You haven't said if this is a sudden fault or if there have been problems previously. Does anything show on the screen? or does it switch itself off before?
Laptop/Notebook. Probably overheating due to fan outlet blocked by dust and muck.
unplug from mains power, take out the battery.
Hold power button in for 30 seconds to clear any residual power.
Clean fan outlets as best you can. Do not blow the dust further in, suck it out (hold vac cleaner nozzle near vent) and clean (using cotton buds)
Connect power back up and see if will start.