There are two areas to look - I will address the easy one:
1. No power (the easy one)
2. Audio / CD does not function once you know you have power . . .
On the power side check to see if you have power.
1. Turn the key to the position that the radio will work without starting the bike
2. If the CD magazine is in the CD Changer press the eject button or
3. If the CD magazine is not in the CD Changer insert the CD magazine
If either 2 or 3 does not function you do not have POWER. Go sleuth fuses and wiring connections.
Place a volt meter (about $1.99 at Harbor Freight these days) on the power connection as shown in the picture. See if you can get at least 12 volts.
If you do not have voltage it should be a simple matter to chase down a fuse or a wiring issue (power or ground).
On the hard side sometimes people take the CD out of the bike with CD's in the magazine still in the changer / player.
On occasion with rough handling the CD's can become dislodged from the trays. Its a simple fix - you need to take the player out of the bike and disassemble . . . they are easy to take apart and put back together.
There can be many other issues but try this first and let us know if you need to look into the Audio . CD side . . .
Good luck . . .