Why can I only get a full phone signal when I am connected to wi fi?

[AC Question]

As of Friday the phone signal indicator has an exclamation mark next to it that only disappears when I am connected to wi fi. This means I cannot access the internet through 3g when out and about.
I have not added any new apps prior to this occurring any help would be appreciated


Thanks

 

[B. Diddy]

Welcome to Android Central! Which phone, and which carrier? Are you certain mobile data is turned on?