If the switch it is plugged into is manageable check the settings on that port. Does the switch port even support gigabit? If it does, it and the aironet should be set to auto and it will negotiate gigabit on its own.
Gigabit ports should be set to autonegotiate regardless. See here: http://etherealmind.com/ethernet-autonegotiation-works-why-how-standard-should-be-set/
A major problem is that many people are also hard setting Gigabit
Ethernet , and this is causing major problems. Gigabit Ethernet must
have auto-negotation ENABLED to allow negotiation of master / slave
PHY relationshitwhp for clocking at the physical layer. Without
negotiation the line clock will not establish correctly and physical
layers problems can result.
If you still have no access to the AP, you will need to manage it directly. The easiest way to do this would be to connect it directly to your laptop via a small static network if you know the APs IP address already. Otherwise you'll need to "console" into it: https://supportforums.cisco.com/docs/DOC-2320