Hello
Their will be a lot of people on here that could be able to help you fix your issue. But you will need to add a lot more information for anyone to help you.
Personally I work as a Exchange Engineer, so I may be able to help you but need a whole lot more information.
What Exchange version, what is the URL you are trying? (should be https://something.something/OWA)
have you try using /exchange instead of OWA.
what error are you getting?
What browser?
Tried on another computer?
Tried on another browser?
Regards
Andrew