Lenovo mobile phone A750 can send short messages but not MMS.

1. Have you inserted two cards? What is the specific situation? Because you can send short messages, the SMS center of your mobile phone should be fine, but if you insert two cards, such as SIM 1 and SIM2, you want to send MMS with SIM2, but the network switch uses SIM 1 network or wifi, then the MMS cannot be sent; See: System Settings-SIm Card Management-Data Connection-Select the card to send MMS;

2. If you use a card, please confirm whether your network switch is turned on and whether you use SIM card traffic instead of WIFI；;

If it fails, please try to reset the system settings-wireless and network-mobile network-access point-select the corresponding SIM card-menu key-to the default settings;

3. If it fails, please try to change the SIM card for testing. If it fails, please handle it according to the fault! (factory settings were restored and failed to be sent for repair)