i would suggest you to follow the following and check if it works??
- Please deactivate all installed 3rd party plugins.
- Delete browsers cache especially cache plugin.
- if any extra codes added by you then remove it.
- Re-save permalinks.
deactivate everything other than wplms defaults then check if it works.
also, ask your webhost for the PHP error log. and share the file here. i will find the error there.
if it does not work then share the admin URL and credentials in a private reply. I will check the issue.