Your data is not lost; that's stored on the hard drive, and from what you've said, that should be recoverable even if the computer is dead.
It sounds like you got the connections to the keyboard wet. Water (or coffee in this case) can mess up electronics in one of two ways: it can short them out if power is applied, and it can corrode the connections over time. My guess is that something got shorted.
Best case scenario, you could replace your keyboard and be back in business. Your options are to fix it yourself or bring it to the Apple store and shell out the cash. If it's not worth the work/money, you could simply remove the hard drive and transfer your data to another computer. From experience though, taking apart a MacBook is not for the faint of heart. There are about a bazillion screws, and half that many little pieces to get to the most simple components.
Another option would be to use a USB keyboard to access your data and copy it to a backup drive.
Moral: if you have important data, make backups because it's not always this easy to get your data back.