How could I resist....
If everything is still just MIDI you can simply transpose the MIDI notes
I am guessing it is not that simple and you have some audio (eg guitars) so I would suggest bouncing down your "backing track" to a single track
Load this track in to a fresh project (to keep your original project safe) and then you have 2 main options
1 Pitch Shift
Select the backing track clip and then go to: Process > Transpose option in SONAR
Make sure you click the "Transpose Audio" option
Choose the "Radius Mix" algorithm for a high quality Izotope algorithm
Make sure you make a note of how much you transpose by as you will need to transpose the vocal back up by the same amount for it to fit with the original project
I haven't used this myself but I think it should give you something good enough to sing to
You would then obviously need to reverse the process on your vocal recording so you can import the recording back in to your original project at the right pitch
2 The old fashioned "vari speed" trick
This was used in the days of tape, where the tape is slowed done to lower the pitch
You would then obviously sing along a bit slower, which will then sound a bit faster and higher when played back at the "normal" speed
Here is a great guide to using this trick in SONAR:
http://www.soundonsound.com/sos/jun14/articles/sonar-tech-0614.htmSecret option number 3...
Do you have Melodyne?
You could try using this technique on your "backing track" to lower the pitch and the the same in reverse in increase the pitch of your vocal by the same amount
http://www.guitarplayer.com/guitar-player-101/1025/tech-tips-rethinking-chord-progressions/49192 Good luck and I would be interested to know how these options work out