503 error is likely caused by crash PHP process, not something we can do about it other than fix the PHP. Maybe the hosting company updated the PHP, or the script uses too much memory, over the limit set by the server admin. It could happen for any web server. You have to contact your host company to resolve this on PHP side.
We will help as much as we could by providing necessary assistances for hosting companies using LiteSpeed, but we cannot afford to be FREE level three support taking care of every thing.