WIN 8.1. Login Password with Vietnamese letter - cannot login anymore
I have a problem with logging in to my Win 8.1. local account (my only account, don't use my Microsoft Account on that laptop):
My System: WIN 8.1, 64bit, Dell Inc. XPS 13 9343/0310JH, BIOS A00 11/04/2014
What happened: I live in Vietnam, therefore have the local standard program for Vietnamese language (UnikeyNT). I added a password to my local user (and admin) account (my only account on this laptop) by typing "....or......" (the points are other letters/numbers). The activated UnikeyNT made "or" to "ỏ" (it is an "o" with a comma on top).
Now, when logging in, I cannot reproduce this letter because there is no such letter in the installed US English (international) or German keyboard. Also, the on screen keyboard does not have this letter.
Any idea how to solve this problem except of reinstalling everything?