If your AOL mail stops working on Android application, you can implement the steps that are given below. But if you do not wish to resolve this matter manually and require technical assistance, kindly dial AOL Mail customer care number and consult the techies for their valuable opinion.
Install recent software updates in the system to make it compatible with AOL mail.
Try using AOL application instead of navigating through Mail application in the Settings every time.
Delete your account from the smartphone and add it back again.
Forcefully stop the AOL application from the settings and re launch it.