The easiest way to isolate the power supply is to plug it in with the laptop off. You should have a charge status LED somewhere on the laptop. If it dies not light up, you are not getting power. Double check the wall cord and the laptop jack; if wiggling either one causes the charge LED to flicker, you've got a connection problem. If it's the wall cord, simply change it out with another cord. With OEM chargers, there are only three types of cords normally used: a two-prong cord commonly used with many other home electronics, a small three-prong connector most commonly seen only on laptops but sometimes seen with other electronic devices, and a larger three-prong connector that is the same as that seen on desktop PCs. You don't need to spend a lot of money on a replacement cord if you don't have a spare. Places like Amazon and Newegg have them for just a couple of dollars and they are all the same for all intents and purposes.
If the connector at the laptop is the problem, there are two likely causes: You have a bad connector on the power supply (unlikely) or a bad jack on the laptop. If you still have warranty coverage, replacing the power supply is pretty straightforward. If the problem is in the jack, it may be deemed to have been caused by your negligence and may not be covered. If that is the case, there is still hope. There are many places that will replace the jack in your laptop for a very reasonable fee, less than $50 in many cases. If you're handy with a soldering iron, you can get replacement jacks from eBay for about $2-$5 or so and save even more money.
If no amount of wiggling the connectors will light up the charge LED on the laptop, you have a dead power supply, a badly broken power jack, or some other more serious problem inside the laptop. Testing with a known-good power supply is necessary to rule that part out. If the power supply is good, the laptop will need to be inspected by a competent technician to determine if the problem is simple enough for a field repair or if a new system board is necessary. If you are out of luck with your warranty, there are plenty of good replacement power supplies out there. Amazon is a good place to start looking. I've found replacement supplies for many laptops for about $10-$15 there.
If your system board is the problem, things start to get a lot more expensive. Sometimes a board can be found cheaply (I've had some luck on eBay from time to time) and all you're out is a couple of hours of bench time for a tech to replace the board. Often, though, a system board will run $200-$300 (or even $500-$600) and that can easily exceed the replacement cost of many lower-end laptops.