By chance have you disabled the feature by accident?
Do the following:
# show web-management
Web Management - Server Configuration
HTTP Access : Enabled
HTTPS Access : Enabled
SSL Port : 443
Idle Timeout : 600 seconds
Management URL : http://h17007.www1.hpe.com/device_help
Support URL : https://www.hpe.com/us/en/networking.html
User Interface : Improved
OR
# show web-management
Web Management - Server Configuration
HTTP Access : Disabled
HTTPS Access : Disabled
Is it enabled or disabled?
if its disabled: configuration > web-managment
If you didnt disable it, did you enable ip authorized-managers?