I was testing my canon ql19 which seems to be in perfect working order. However I pressed the safety catch and set the camera to bulb mode and I can now not turn the ring back again. How are you meant to remove the B setting?
I'm not sure about this "safety catch" button. There's nothing in the manual that leads me to believe that something like that exists (http://www.cameramanuals.org/canon_pdf/canon_canonet_ql19e.pdf) Manual linked from Mike Butkus, who does awesome work in assembling these old manuals. Consider throwing the man some money @ https://www.butkus.org/chinon/donation_policy.htm
In general, though, attempt to "clear the slate" and start over. Wind the film advance lever making sure you get a full crank. Then use the shutter release. At this point, you should be able to adjust your shutter speed. With bulb mode, hold down the button and hear the shutter open. Keep it held down. Release a moment later and hear the shutter close. If you don't hear it close, then attempt to push the button again and it should close.
Please point out the button that you call "safety shift" as it's possible the use may have impacted the camera function. (If it's the self timer, and the self timer mechanism is broken...then you wouldn't be able to clear the slate)