If you can't get your S3 to connect no matter what you try, your last option is to perform a complete factory reset. This will delete everything on the phone, so you'll want to back up anything you want to save onto an SD card if possible. You can insert an SD card by removing the battery on the back of the phone. This will display the files on your S3. This will switch the display to all of the folders on your S3. This is the emulated SD card that stores all of your files on your S3's hard drive. This will highlight all of the files and folders so that you don't miss anything. All of the selected files will be copied so that they can be moved to the SD card. This will open the storage for the SD card you inserted. This may take a while if you have a lot of files. Once your files are backed up, you can export your contacts to the SD card as well:   Open the Contacts app. Tap the "Menu" button and select "Import / Export." Select "Export to SD card" and then tap "OK." Once you've finished backing up your files and contacts, you can safely reset your phone. You can do this from the Settings app. This will open the factory reset menu. After confirming, all of the data on your phone will be deleted and your operating system restored. This process may take a while to complete. You'll be taken through the initial setup process for your phone. Log in with your Google and Samsung accounts to begin using your phone again. Once your phone is powered on and you're logged in, try the connection with your computer again. If you still can't get the S3 to connect and you've tried everything listed above, you may need to get a replacement device.
أدخل بطاقة ذاكرة فارغة في الهاتف. افتح تطبيق الملفات. انقر على زر "كل الملفات". اختر مجلد "sdcard0". انقر على زر القائمة ثم انقر على خيار "تحديد الكل". انقر على زر القائمة  ثم انقر على الخيار "نسخ". انقر على خيار إخراج البطاقة إكزيت إس دي كارد". انقر على خيار "لصق هنا" وانتظر لحين انتهاء عملية نسخ الملفات. احفظ نسخة احتياطية من جهات الاتصال. افتح تطبيق الإعدادات. انقر على لسان تبويب "الحسابات" ثم اختر النسخ الاحتياطية وإعادة الضبط". انقر على خيار "إعادة الضبط لإعدادات المصنع" ثم على خيار "إعادة ضبط الجهاز". اضبط إعدادات الهاتف. حاول توصيل الهاتف بجهاز الكمبيوتر.