Hi Carol,
Thank you for sharing your question. I understand that your keyboard is not working. I am here to help.
Based on my knowledge, this happens if the driver is missing or needs to be updated or needs some tweak.
Here's how you can try to fix it.
See if it works in BIOS. Restart your laptop and hit F2 (or Del, depending on your Dell) to get into the BIOS settings.
If it works there, the problem is probably with software or drivers.
If it doesn't, it could be the hardware or how the new keyboard was put in.
Plug in a different keyboard
Try a USB or Bluetooth keyboard with your laptop. If that one works, the problem is just with the built-in keyboard.
Update BIOS, Go to Dell Support and type in your laptop’s Service Tag.
Get the newest BIOS and chipset drivers for your model.
Be careful to follow Dell’s directions when you are updating the BIOS.
If driver updates don't work
If you get an updated message, run Windows Update first to get your system up to date.
Contact Dell again
May I also ask did you try testing the keyboard in BIOS or with another keyboard? This will help me figure out if it’s a hardware or software thing.
I hope this answer is helpful, if you have any questions feel free to reply.
Best Regards,
Noel