14 wk Baby developed sleeping problem!!

My baby ever since he was born has always been set down at night awake and got himself to sleep, never any crying or fuss. Now though he is 14 weeks old and in the same routine and has decided he doesnt want to sleep day or night!! He has had to be rocked to sleep or had the hairdryer on for the last week to get him to sleep at night.

Has anyone else found this has happened?! And if so please tell me how to help him get back to how he was, I really dont want to have to get in to the habit of ricking him etc

Thanks!

xxxx