https
/support.lenovo.com/us/en/solutions/ht500222
how to access the BIOS.
The BIOS or Basic Input/Output System is a small operating system that the computer relies on to power on, this OS tests the RAM and other basic functions and then loads the Main OS. inside the BIOS you can changes settings that can effect the system either positively or negatively - make no changes just test the key. booting into this OS, the BIOS will offer you a way to test the actual hardware (the right arrow key) the arrow keys are used to navigate the BIOS. if the key does not work here the key does not work.
youtube is your friend here. IDK the model number you have so this is the first thinkpad keyboard replacement video I stumbled upon. search your model for more detailed instructions if you need to replace the keyboard.
https
/www.youtube.com/watch?v=Nl9BIgaakXg