Sierra stuck at login screen - password doesn't work This has happened to me twice in the past week.  I put my MacBook Pro to sleep while my user account is logged in.  When I return, I enter the correct password and it shakes, as if the password were wrong.  I try several times, and get nowhere.  So I force reboot, and then I am able to login again.  Here are some relevant lines from the log right after the reboot.  The opendirectory lines are repeated hundreds of times.

loginwindow: -[LWBuiltInScreenLockAuthLion verifyPassword] | ERROR | Verify password called with PAM auth set to YES, but pam handle == nil
opendirectoryd: Client: &lt;private&gt;, UID: 0, EUID: 501, GID: 20, EGID: 20
opendirectoryd: queuing request to connection - '&lt;private&gt;'
loginwindow: (libpam.2.dylib) in od_record_create(): failed: 13
loginwindow: (libpam.2.dylib) in od_record_create_cstring(): failed: 13
loginwindow: (libpam.2.dylib) in pam_sm_authenticate(): OpenDirectory - Unable to get user record.


This is running Sierra 10.12.6.  Filevault is disabled.  I also notice after the reboot, Spotlight is hogging CPU for several minutes, like it's rebuilding an index, but that might be a red herring, just caused by the reboot.
Try to reset your login password at first:

macOS Sierra: Reset a login password.

If the above didn't help, try to reset Nonvolatile Random-Access Memory and System Management Controller:

How to reset NVRAM or PRAM on your Mac.

How to reset the SMC on your Mac.

P.S. I experienced the same issue on Mac Mini with El Capital. Resetting PRAM and SMC helped me to fix it.