Might check your manual, normally there's a Function key or combo to unlock it, else can do in affect a hard reset, shut down, uplug, remove battery, and then hold the power button on for around 20 seconds or so, then battery back in, plug in AC adapter and give it a try
It also may have gotten unplugged somehow from motherboard. As an absolute last resort try pulling the keyboard up from the laptop. you may have to remove the plastic trim from the top most part of the laptop. It would sit right under the monitor and run the entire length. Likely is where the LED indicators are housed. This will allow you to get at the screws that hold the keyboard down. unscrew. lift keyboard. See if plugged in correctly. As stated above this is a last resort. Especially if you're new to this sort of thing.
Does it work long enough for you to get into the Bios? Try rebooting and pressing the correct key when the bios indicator comes up. If you can get into bios and the keyboard is accessible while in bios mode then it's likely not a problem with your keyboard itself being locked. You may have something set up wrong in your operating system. Check to see if you have correct and up to date drivers for your keyboard. You can do this by going to the control panel and clicking device manager. Find keyboard and right click and click update drivers.
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