1. Check the Num Lock key

BitLocker key is a numeric password. Therefore, the Num Lock key might be disabled. Press the Num Lock key at once and see if you can type the password. You can also use the numeric keys in the number row (the keys above the alphabetical keys on a keyboard).

On the BitLocker screen, the function keys also work the same as the numeric keys. You can also try typing your password.

2. Perform a hard reset

Hard reset your system and see if your keyboard works after that. Follow these steps:

1. Force shut down your computer by pressing and holding the power button.
2. Remove the power cord. If you have a laptop, disconnect its charger. Also, disconnect all peripherals.
3. Press and hold the power button for 30 seconds.
4. Connect the power cord and turn on your system.

3. Use a wired keyboard

If you have a wireless keyboard, use a wired keyboard. Connect the keyboard to all available USB ports. Sometimes, front USB ports do not work on the Recovery or BIOS screen. Connect your keyboard to the USB ports available on the back side of your computer case.

4. Use a PS2 keyboard

Some motherboards support PS2 input devices. These PS2 ports are available on the back side of the computer case. Look at the back side of your computer case and see if your motherboard has such ports. If yes, connect a PS2 keyboard to your system. If you do not have a PS2 keyboard, use a USB to PS2 adapter. The PS2 port should work on the BitLocker screen.

5. Clear CMOS

If the issue persists, you can try clearing the CMOS. This step also resets the BIOS settings to default.

1. Turn off your computer and wait for a few minutes.
2. Open the computer case and gently remove the CMOS battery from the socket.
3. Wait for a few minutes and reinsert the battery with the right polarity.
4. Turn on your computer and try typing the password on the BitLocker screen.

If this works, you can apply the same BIOS settings later.

6. Disable Fast Boot in BIOS

If the problem persists, you can try disabling Fast Boot in the BIOS. Fast Boot is a feature in BIOS/UEFI of modern computers that reduces the startup time by skipping certain hardware checks. Visit the official website of your computer manufacturer using a working computer and download the user manual for your computer. Check if the Fast Boot option is available on your system.

In most cases, clearing the CMOS also disables the Fast Boot option, as it resets the BIOS to its default settings. However, if you cannot enter the password on the BitLocker screen even after clearing the CMOS, you need to access the BIOS to check whether this feature is enabled. Try this:

Force shut down your computer. Press the power button and immediately start spamming the Esc key. See if you can enter into BIOS. You can also enter BIOS through WinRE. Since the keyboard is not working on the BitLocker screen, the chances that it works in the Windows Recovery Environment are also less. However, you can give it a try. To enter Windows Recovery Environment, interrupt the normal boot process by following these instructions:

1. Force shut down your computer.
2. Press the power button. When you see the Windows or manufacturer’s logo, immediately press and hold the power button to turn it off again.

Repeat these steps until you see the Preparing Automatic Repair screen. Once you are in WinRE, see if your mouse works. If yes, select Advanced Options > Troubleshoot > Advanced Options > UEFI Firmware Settings.

The methods for disabling Fast Boot in the BIOS vary by motherboard. I have explained the method for ASUS computers: