A. Is it plugged in? (not trying to insult you)
B. unplug it and replug it.
C. unplug it and replug it in a different outlet.
D. gently swish your filter media in tank water and replace.
E. If all else fails go buy a new filter
BTW dump a few cups of tank water into the filter every hour to try to save as much bacteria as you can. Also if you have an airstone I'd use it, If it's very small you might think about putting it in the filter. Filter's die eventually. Maybe you have a warranty on it. I hope someone else helps you because I don't know very much about filters.