Generally you can do a few things to narrow down the problem. It's unlikely that after only 2 years you would have such a major hardware problem as your graphics card getting shot.
Firstly, are your graphics (and other) drivers up to date? If they aren't it can have severe side effects on performance.
Secondly, have you installed any software (or hardware) recently, if so this recent installation could have had negative effects on your laptop, try and recall if you did and uninstall the software (or remove the hardware).
Thirdly, have you ran a virus scan? There may be a virus on your system purposefully slowing it right down.
Fourth Point, have you posted on the forums of your laptops manufacturer, often these problems are not small isolated cases and can be affecting users world wide, if that's the case then you can often find a lot of information on the manufacturers website/forums. If there is no information, then don't worry, posting on there forums is a place to start! You never know, there might be other people like you who you can talk to.
Fifth point. Contact Customer support, as mentioned above, this might be a common problem, and they may have an easy fix for you, you never know!.
Other things you can try - You could try a system restore to a previous date when you knew that your laptop was running at a higher performance. Remember to back up your data first. And if you are unsure what to do, look at some online tutorials on all the necessary steps, just to be safe.
You can also reinstall windows, this often can restore your computers performance to what it used to be (depending on the problem of course), I don't recommend this until you have exhausted all other options.
I hope this helps! Post back if you end up fixing it or need more help!
Cheers - JD