I had this problem on my 1320, hard reset did it. I think you should check your connection, go to settings >mobile+sim>sim settings >network selection >(search for the networks manually)
Sometimes only 2g is available, so if it says 2g, you cannot have a 3g connection. Also check mobile+sim>highest connection speed>3g
If all the above is ok with you & still you don't get a 3g connection, you need to reset your phone(all the data would be lost)