So I've been working on a project, and everything has been normal, except recently I saved and exited out of the project. When I opened it later everything was there, but every single track was silent. The green bar at the left side of the screen still fluctuated as if sound was being made, but no sound would come, and even more strange is that if I added new VST's those would make sound unlike the ones already there. I'm not sure what's going on, but I feel like it is fixable and I simply lack the knowledge.
Thanks in advance! 

Is your master buss showing signal? If so, check and make sure that it's output is set correctly.

Check and recheck every possible setting: channel assignments (both in sonar and in synths); volumes, velocity, etc. I sometimes find that I have put a volume change in the event list, and inadvertently set the value to zero!

My master bus is showing signals, I'm not sure exactly how to check it's output however. I'm using Sonar X1

In console view, it should be under the fader. You might have to go to top left of the console view and check the option to show the outputs first.

I found the problem and resolved it!! Thank you all so much for your help

Just curious - was that the problem, or something else?

Yup, somehow everything's output got set to nothing, so every track was still functioning, but had nothing to play through.

You might want to mark the Thread Title as "solved", so users will know.

It doesn't hurt to have a proper title either.
Every other thread is about needing help.