Hello mate,You could try giving it a good blast with an air line,failing that take it apart and give it a good clean. Laptop or Keyboard? BTW you have an onscreen key board for the time being,type OSK in the windows search box bottom left "Start.
You need to determine if the problem is with the membrane or the controller chip, you can do this by plugging in a USB keyboard. If that works fine then it's the keyboard and not the chip. Laptop keyboards are usually easy to replace and you'll find a guide on YouTube or simply by doing a Google search but if you become unstuck let me know and I can help you out. The best way to find a keyboard is using Google shopping, just type in your laptop model + keyboard i.e. Toshiba satellite Pro A1 replacement keyboard OR you can remove it and directly type in the part number from the sticker on the bottom of the one you remove. Just google search then choose "shopping" from the top menu to get to their shopping page.
Oh by the way I've seen this problem hundreds of times and it's usually crumbs under the keys to be honest and you can just turn the laptop upside and tap the bottom and blow the keyboard, this usually works without the need for compressed air, if you spray a keyboard without it being upside down you usually just end up pushing the crumbs around. I should have said that first really LOL