The problem could be the result of either network issues or a software problem with the phone. Depending on the cause of the MMS problems, you may end up completely wiping your phone's data.
Check the Android phone's network connection if you can't send or receiving MMS messages. An active cellular data connection is required to use the MMS function. Open the phone's Settings and tap “Wireless and Network Settings.” Tap “Mobile Networks” to confirm it is enabled. If not, enable it and attempt to send a MMS message. If you are outside your provider's network, enable data roaming to use MMS, although the MMS features may not function properly until you are back in your provider's network.
A soft reset clears up a range of issues on Android phones. If MMS problems persist, soft reset your phone. The soft reset, or battery pull, does not negatively affect your phone. Send a test message to determine if the problem is resolved.
A last resort option for fixing MMS problems on the Android phone is a hard reset. The hard reset removes the data on the phone and resets its settings. Back up your phone's files before doing a hard reset.
Hope that helps!