Here are some troubleshooting steps that may help in solving the issue.
- Start by connecting an external USB keyboard and see if the same problem will persist.
- Next to try is to try to log in Safe Mode, while the laptop is booting up repeatedly press on F8 until it loads Advanced Boot Options, select Safe Mode and press Enter.
- If all these will not work, do contact Acer Support about password related concern first.
- http/www.acer.com/ac/en/US/content/support#_ga=1.64263791.1950423068.1441902574