The controller shouldn't have lost the module ID or name, unless you removed the product. Otherwise it would stay on the controller as a saved entity.
If the product has been removed from the controller memory there are three possibilities for your not seeing the module now:
1.) Password problem. Solve with password reset
2.) "Ghost" module problem. I haven't seen this in a long time, but it's happened before. A module gets somehow partially deleted....the space on the controller screen is still present for that locomotive, but there is no picture and no name, and it is unable to be selected. It's there but it's not....therefore a ghost. Solve by contacting Ring Engineering.
3.) Module failure. Very rare, but it can happen. There have been extremely few failures or shorts of modules in the years that Ring has been producing Railpro. Solved by sending the module to Ring Engineering and they will repair/replace as necessary.
As a side note, why did you remove the module with the offending sound file, when you could have just installed a different sound file? Don't forget that Railpro modules are completely update-able. You can load any sound onto any module. So if you don't like something, just delete that file and load the one you want. If you're unsure of how to do that, let us know. We can walk you through everything.
-Kevin