CANT CALL OR TEXT!!! please help!

[HyeRinLuv]

Before I went to sleep i was able to text and call but when i went to sleep and woke up i couldn't. At first i thought it was just that the signal was bad but my brother has the same phone as me and his phone worked perfectly. I can go on facebook, post things on instagram, watch videos on youtube, go online, and take pictures but I JUST CANT CALL OR TEXT! I'm so confused and if someone out there knows whats going on with my phone then i'd be really thankful if you could reply