Marketplace/picture messaging

I have a Dell Venu Pro Windows 7 cellphone. It was previously owned by my roomate. We have the same service provider but for some reason I can no longer use picture messaging not access Marketplace. Whereas when my roomate had the phone there was no problem. She has a new Dell cell same type as my cell and she can access those apps with no problem she can also use pic messaging. Can you please help me with this issue.

Thanks,

Joanne Fleming