Exchange 2010 / outlook 365 work

We tried to change our domain on exchange over christmas and it failed, we think because we also have a local domain controlled from the same machine with the same name. We have exchange 2010 with some users on outlook 2010 and some on outlook 365.
Since we couldnt get the new domain working we tried to change everything back to how it was. Now its mostly not working properly. Most of our staff are not on remote html email and thats not working well either.
I could do with someone who knows exchange2010 and outlook and can remote in to move the email domain and instruct us on what to do to get it all working again.
This is going to be a piece of cake for someone who knows the right configuration. (We mostly know what we are doing but this has stumped us)