And, if you're not a computer tech or have a high degree of mechanical ability, you can destroy your laptop by trying to open it up yourself. There are little connectors in there that were never designed to be taken apart. Don't ask me how I know....
But what you can do, without destroying the laptop, just blow some compressed air into the exhaust port on the (side of) laptop. If you get a puff of dust and dirt out of the intake port, you're on the right track. If you can look in the air intake port and see the fan, see if it's even turning.
And if you're going to blow air into the intake port, use something like a toothpick to keep the fan from turning while you blow air into that area. Over driving the fan with compressed air can result in a blade flying off or damage to the fan's little bearing.
If you don't feel comfortable doing any of the above, then take your laptop to a professional for proper cleaning. It's better to pay a few dollars for cleaning, than to destroy an otherwise good laptop.
Good Luck, and Happy 2018!
TechnoMage
