You are posting in the management section, and I assumed your appliance is a management server. If this is the case, you can stop it, it will not affect network connectivity.
If it is a security gateway, you will have to set up a service window. However, it is is a member of the cluster, you still can stop it without breaking connectivity to your users.
That said, there is no other way to restore your password, unless you have admin password for your management. Please let me know if this is the case or not.