Would be to search online for "phone won't send pictures anymore"  various threads with solutions come up based on type of phone, whether you are trying to send with text or email, etc.  When in doubt do a hard restart on your phone.  That seems to solve most of my iPhone issues.  Good luck, technology can suck for us amateurs.

I had a similar problem sending photos with my smartphone earlier this year.  I was advised to completely turn off my phone, then restart it.  That did the trick for me.  It's the same concept as rebooting your computer.

Although you didn't say which type of phone. I am not a Droid user, so I'm lost in that area but this has happened to me with my iPhone and it is a simple setting that was changed within the message settings. If you are using iOS, make sure MMS is turned on within your messaging settings. If it is not in the on position you will have all the other options within the photo you're viewing such as email, twitter, print, copy, etc except the option you need-message.  

It is also true that our phones need to be shut down and restarted as others have said. Way back in the day of the Motorola Razr I was experiencing a lot of difficulty and called T-Mobile customer service. A simple reboot of the phone solved all the issues- the rep advised me that it is true our phones need to be powered off completely on a regular basis.  

Maybe you've resolved the issue by now and you're back in business...good luck!

Peace,

Astri