Does anyone know how to create a daily automated backup of the Marketo instance.
And setting up a roll back?
Nope, you can't make your own restorable backup.
The Bulk Extract API together with some of the paginated (non-bulkified) APIs enables you to build an offline copy of some of the parts of your instance, but nowhere close to all. And even those parts you have offline can't be restored: for example, you can't restore leads with their original IDs because that's a system-managed autoincrementing field.