Check whether the problem affects every device. Restart your router and any firewall, then check for an outage with your provider. If only some devices are affected, your internal network may be the cause. Write down what changed recently, as it can speed up diagnosis.
A stolen password alone should not open your email. Multi-factor authentication adds a second check at sign-in, which makes account takeover much harder. Turn it on for every user, starting with administrators.
What is being backed up? Is a copy kept separate from your main systems? When did you last test a restore? A backup you have never restored is only an assumption.
Automated assistant. Answers can be wrong, so please call for anything urgent and don't share passwords or payment details.
