Hi Carol, this is a big issue at the moment a lot of Outlook users are affected, this is expected to be fixed within the hour, a lot of users are reporting they can access their Email from their Mobile phone, but not their PC/Laptop . . .
Microsoft are seeing a few isolated incidents on a small portion of infrastructure that has received the fix and that did not work. They are analysing diagnostic data and service log files to identify why the fix was ineffective for some of their customers.