Everything's working, just no sound.
Isn't that a contradiction in terms?
All of the requests for further info are genuine to help you, not waste your time, or more importantly ours.
"No Sound" with a soft synth could be caused by several dozen different things. All we need to know are you basic set up.
Answer these then...
Soundcard. Onboard? External?
Speakers? Powered or plugged into an amp?
How are they connected to the computer, via the onboard soundcard or a 'proper' interface?
Softsynth? Which one? Is it on an instrument track or a separate MIDI track and audio track?
Is it playing back MIDI data from a track or are you playing it via a controller in real time?
Have you checked the sound card drivers in Preferences->Audio devices?
DO you have any busses in the project at all? Can you hear audio tracks okay? Have you ever had it working?
That'll do for starters................
Unfortunately Sonar isn't something you open up and then get on with it. It takes a bit of time to set up and learn.
I'd suggest reading the manual especially Tutorial One, if you're still getting problems after that then come back with the info I've asked for above and you'll find lots of very helpful people on here. But "It's working okay but I can't hear anything, I just want you to tell me how to fix it" isn't going to get you much help I'm afraid.