If your phone is jailbroken, some plug-ins may hide icons. You can move the menu to the far left to search, and try to search for the system icons that have disappeared, such as settings, and see if you can find them. If you can, it means that your icon is just hidden. You can restore the hidden icon by setting related plug-ins. SBSettings can hide the icon, please check whether the plug-in is installed, if so, please enter the plug-in to reset the relevant settings. If it is hidden by other plug-ins, please check the tutorials of the relevant plug-ins.

I hope my answer can help you ~