Greetings!
I am using as Zoom R16 as my audio interface and control surface.  I have been using this successfully for a few years now, all the way from 8.0 through to X2a.  Now all of a sudden the interface won't show up in the listing. I have also used ASIO4ALL and a Behringer driver.  These two show up but the ZOOM does not.  Without the Zoom I am unable to do simultaneous 8 channel live recording, so I'm kinda shut down.  I need all the help I can get.

Are you plugging the Zoom into a different USB port than what you normally use? It's a long shot, but sometimes devices are "wedded" to particular ports. If you plug into a different port you should get a prompt to install driver software.
 
If you are plugging into a different port, try plugging into the same one you used originally. If you are plugged into the same port you used originally, then try plugging into a different port - if you're lucky, you'll be prompted to install new driver software, it will install, and your interface will work again.
 
Also, don't know if the R16 has a dedicated driver or whether it's class-compliant and doesn't need a driver. If it's class-compliant, then it's probably not ASIO and ASIO4ALL or a Behringer driver won't help. Can't give you much other advice without knowing more...

I tried both of my USB2 ports after removing and reinstalling both the R16 and the ASIO4ALL drivers, and watching Windows7 complete the installation of the driver.  With both drivers I made sure that they the latest drivers (they were both the most recent drivers already and had been for quite a while. but I re-downloaded them anyway.)
 
Until last fall I would switch back and forth between the R16 at home and a Behringer UCA02 interface when I was away.  Even when not attached the Behringer name was always listed, along with the ASIO4ALL, but the Zoom R16 would sometimes not show up although it was attached.  I would have to uncheck the Behringer, save the project and close Sonar.  Upon reopening, the Zoom would show up and I could connect to it.
 
Funny thing is that the R16 would always show up as a MIDI device and as an option for a control surface.  It just won't show up as an audio interface.  ALSO, even though it wouldn't show up, if I disconnected it from my laptop, SONAR would pop up the message informing me that the R16 had been removed and give me the yes/no option for retaining the path.
 
So ... it's there, and it's not there, and I can't get to it.
 
Let me know if there are other specifics needed.
 
(HP PAVILLION, WINDOWS 7 64bit)

try renaming the AUD.INI in your user directory/AppData/Roaming/Cakewalk/your version of SONAR and restart SONAR.

I imagine you've done this already, but try hitting the USB button, terminate, enter, reset.  Also, if you're running the R16 on the AC adapter, unplug it and see if it runs on USB power. Is it shown in audio devices in the Windows control panel?

Try uninstalling ASIO4ALL then reinstalling the R16 ASIO drivers. I know ASIO4ALL has its fans, but I've run into all sorts of problems with it installed in terms of interfering with other drivers.

I am having the very same problem. The only difference is that I am not using the ASIO4all driver. It just started doing this a couple days ago out of the blue. I have been using the r16 for a couple years with no troubles until now. I am using X3d with windows 8.

Probably best to start a new thread to be honest otherwise we will get your different issue muddled with the OP's.
In the meantime please checkout the advice on this thread, update to the latest drivers and firmware etc etc.
 
Cheers
 
Alex

Forget the Behringer drivers and ASIO4all driver. Behringer drivers are written for Behringer and ASIO4all is just a WDM driver wrapper. so you need to install and use the ZOOM RX16 Drviers. Those are the drivers that are written for that card.
 
Then run the wave profiler and select the zoom
 
Cj 
 
 

If it needs ASIO drivers then the Sonar Wave Profiler won't find them as it it is specifically for Windows type drivers eg, MME, WDM/KS etc but not ASIO.

I really wish Cakewalk would terminate the default use of the Wave Profiler especially as they always recommend using ASIO drivers if they're available.