There are any number of things that could have been affected by your power outage. The files may have been damaged by the uncontrolled shut down. The system that hosts the file to others may not be functioning as it was before.
You might start by describing your set up and what, if anything, you've tried to correct the problem.
Is this a solution hosted by server or FileMaker Pro, Hosted over the web or ?
Have you checked your files for possible corruption?