You'll need to grab the error logs from the Panel. The following command uploads the last 150 lines of this day's log to our pastebin and provides a link you can share.
tail -n 150 /var/www/pterodactyl/storage/logs/laravel-$(date +%F).log | nc pteropaste.com 99
#Help
uneven hillBOT
viscid flare
cunning plover
https://ptero.co/unogokumid
"panel" database does not exist or the "pterodactyl" user does not have access to it
viscid flare
Can I fix it without losing data of my servers?
viscid flare
"panel" database does not exist or the "pterodactyl" user does not have access t...
??
cunning plover
Can I fix it without losing data of my servers?
I suggest you to backup .env and MariaDB before doing so