Mac Keyboard Broken

Hello, my keyboard is having some problem. My keyboard was attached with iMac 27 Mid 2011.

The problem is that it sometimes it automatically enters Lunchpad and leaves Lunchpad quickly without pressing the shortcut or clicking at the Lunchpad icon. The second problem of it is that when you press a key, it inputs 2 keys. For example, if you press 2, it inputs "23"; if you press 3, it inputs "23".

The room conditions are fine for the keyboard, and I'd never broke or pour water on the keyboard, it still works fine yesterday :/

Any solutions?