Network was compromised need to restore database to new server

We experienced an incident with ransomware and attempted to backup and restore financial edge into a new server. We are running issues due to the original system administrator leaving and not providing access prior but also having issues with backing up from old server and initiating restore into new server. Has anyone come across a similar situation or could possibly provide some advice to how to get back online and allowing our accounting team to access financial edge again?

we are a non profit organization that provided mental health services to the communit. we are also in audit along with preparing for fiscal year end closing. Very appreciative to any help that can be provided from this community!