A phone may slow down or no longer respond, or an app may generate an error pop-up and be terminated if the storage space or app execution memory is insufficient. You can secure more available memory space to avoid such problems.
Securing more memory
Tap the Recent apps button '□' on the Home screen. Drag an app horizontally or tap 'X' to delete the app. Tap 'Clear all' to delete all recent apps in the list.
Using Smart Doctor
It shows the apps and data that are not used but still occupying memory space. You can delete them as needed.
Go to Settings> Select 'General' tab> Smart Doctor.
Please note that the content in the download folder will all be deleted when you clean up the download folder.
Using the virus vaccine app
Download a vaccine app from Google Play Store and install it. Scan your phone for viruses and malware.
If the phone is stopped because of an unauthorized app, you can solve the problem by delete the app causing the problem or initialize the phone after backup the personal data.
Please note that you can lose valuable personal information if you initialize your phone without backing up the personal information first.