I have a Canon 1200D and I just tried to use the Neewer tt560 speedlight (which works with an older canon of mine). I keep getting the message "Menu not available. flash is off or unsupported, or an accessory is attached." in the External flash settings. I've taken the shoe off and tightened screws and cleaned it. I am having a hard time troubleshooting the problem. any suggestions?
There is no problem. Your Newer TT560 will work just fine with your EOS 1200D but it is an "Unsupported" Manual flash.
It is not compatible with Canon's in-camera flash menu, and that is why you are seeing the "Unsupported" message. The in-camera flash menu was designed to be used with Canon ETTL flash units produced after 2007. This includes flash units like the. 430EX II and 580EXII. Older Canon flash units like the 430EX and 580EX are not compatible and will display the same message. Some 3rd party ETTL flash units are also compatible, but any non-ETTL flash will not be.
I suspect your older Canon camera predates 2007 when can first introduced their in-camera flash menu on their cameras.