Have you tried connecting a Wired keyboard? A USB one would be connectable and help you test, as wireless ones can have other problems that make using them to test less reliable.
Since you will need to get past the password to do anything, other than doing things that many not need to be done, I would try connecting that kind of keyboard first to see if you can gain access.
If you can get in that way, then do the following.
1. Uninstall the keyboard driver.
2. Reboot the computer. (yes without reinstalling the driver).
3. The computer should reinstall it on its own when it restarts.
See if that fixes it.