紧急求救laptopkeyboard!!!!

There is something strange for the keyboard of my laptop.
One key can not bounced up, so even I do not push down it, it is held down. As a result, the computer can not work at all.
I checked the keyboard, it was designed so that no dirt can go in.
Before that, I didnot do anything else except updating the system of my computer
Could you please let me know whehter the keyboard of a laptop computer can be replaced easily?
What should I do in such kind of case?
Thank you very much for any suggestions and help!!!