cannot log into GUI over web

Hey everyone,

Our IT team has set up our new firewall, before initial configuration we were loggin in directly thru the management port with the default IP. We set up web loggin tested it and it was successful. Next day I tried to access the firewall again via web but now the address is dead. 

Can anyone tell me where and why I cannot access the firewall over the web? has the address changed? might one of my configurations messed something up? I cannot find where in the GUI I set up the web access. I am very new to firewalls so this will be a good learning experience for me.

thank you for taking the time to read my post and thanks in advance for your help.