Nissan Altima: NO POWER TO RADIO

I just installed a new cd/mp3 player in my 98 altima. Before i placed it in
the dash i tested the connections and it worked perfectly, the display,
radio, cd, and all speakers were working. Then i disconnected it to put in
the proper harness. Then I plugged everything back in and it wouldn't work.
None of the things i listed above were working. I thought maybe it was a
problem with the cd player so i connected the factory radio back up but
got the same result. The only thing that was working on the factory raio
was the lights on the buttons. I thought there might be a blown fuse so i
changed it. Nothing happened. Can anybody shed any light on this at all. I
put everything back the way it was and nothing is working still. PLEASE
HELP!!!

-Rick888

hey thanks for the help, i figured it out though, seems theres a fuse box
in the car as well as under the hood. Didn't know about the one under the
hood. Everthings running now. Thanks tho,

-rick888