Just a thought - have you configured your locale correct ? I know - you say it work at first but then it doesn’t - makes me think of
/etc/vconsole.conf//etc/locale.gen/etc/locale.conf
A correct configured system would have something like this - the first file is shortened for brevity
$ ls /etc/locale.gen
# Configuration file for locale-gen
....
#zu_ZA ISO-8859-1
###
#
# Locales enabled by Calamares
da_DK.UTF-8 UTF-8
en_DK.UTF-8 UTF-8
en_US.UTF-8 UTF-8
$ cat /etc/locale.conf
LANG=en_DK.UTF-8
LC_ADDRESS=da_DK.UTF-8
LC_IDENTIFICATION=da_DK.UTF-8
LC_MEASUREMENT=da_DK.UTF-8
LC_MONETARY=da_DK.UTF-8
LC_NAME=da_DK.UTF-8
LC_NUMERIC=da_DK.UTF-8
LC_PAPER=da_DK.UTF-8
LC_TELEPHONE=da_DK.UTF-8
LC_TIME=da_DK.UTF-8
$ cat /etc/vconsole.conf
# Written by systemd-localed(8) or systemd-firstboot(1), read by systemd-localed
# and systemd-vconsole-setup(8). Use localectl(1) to update this file.
KEYMAP=dk
FONT=lat2-16
FONT_MAP=8859-1
XKBLAYOUT=dk
XKBMODEL=pc105
XKBOPTIONS=terminate:ctrl_alt_bksp