First of all you should have below thing:
1. A WiFi Internet Modem or You can make your laptop WiFi Hot-spot using this trick.
2. Android phone or tablet
3. Obviously a computer or laptop Now just follow these steps.
Now just follow these steps.
First of all connect your phone with WiFi.
Now WiFi File Transfer from Google Play Store.
Now open My Computer in your computer of laptop. Here just fill the the ftp address in address bar as shown in below screenshot.
Now you will see that you file manager of your phone in your computer. Please note that there is no need of internetin this. You should have only WiFi connection in both device.