Wordpress MultiSite Fix/Repair

Hello,
I had some freelancers here on this platform work on my WordPress membership platform that runs with multisite since it has large premium plugins.

All of a sudden, I can access the MultiSite dashboards and cant even access new sites if I create.
Also the URL changed from an URL extension to sub domain??

Someone did something that broke my site and I need to fix it.

I have a managed VPS w/cpanel.

Can you help with this?

Thanks
Derek