This depends on many factors, such as the complexity of your object. In some cases you can simply undo your changes that caused this issue by using the back/undo button at the bottom left of your Shapr3D screen. However, if you have made many changes since the parts became joined those changes may be lost.
Can you share screenshots of the issue? This may help explain a possible method to undo the joining.
Don’t be sorry for the questions, please ask away that is one of the reasons these forums exist. Asking questions can speed up the learning process. We all (or at least I do) make these mistakes while learning and even after experienced. I make them frequently, but I keep exploring the app and its possibilities. Sometimes doing something a different way or in a different order gives the end result you want.
The more info you can share, screenshots, the file (where possible), a video or the issue and a description of the issue and what you need/want to do may help us to help you.