Why can't I send nor receive picture messages?

[runoe]

My iPhone 6 is not receiving nor letting me send photo messages. Every time I try sending one, it says failed. Friends also have sent me photo messages but I never receive them. iMessage, SMS, MMS are all switched on. I have not recently changed any settings or downloaded an update. Advice?

 

[happyjess]

What about your cellular data? You have to turn it on in order to send and receive pics