@gendrona
Hi,
1) You can try to replace the specific file again from default joomla installation package/unzipped package as you are using hathor admin template
Path : /administrator/templates/hathor/login.php
2)Or better yet, You can even replace the complete folder -- /administrator/templates/hathor/ however taking backup would be suggested if case you have done customizations
3) Kindly ensure to clear your browser cache in case changes dont reflect