Help with my cell phone?

I have had the sanyo incognito from boost for a few months now and since this morning i have not been able to text verizon numbers. I can recieve a text but if i reply it does not go through to them. Its only with verizon, i can text other services such as revol, virgin mobile, and others. Can someone explain to me what is going on? And possibly how to take care of this? Thanks :)