Reprogramme Megane After Battery Disconnect?

Hi,

I have disconnected my battery in my Megane to attach a power cable for my amp. It was only disconnected for half hour max. I have connected my battery and everything works in my car like windows, lights, ignition etc. The only problem is my clock, radio & trip computer all reset each time i leave the car, and lock it.

It says in the manual that i need to reprogramme my car but i have no idea how to do this. Can i do this myself or would i need to take it to a garage?

If i do need to take it to a garage how much am i looking at as surely i don't need to do this every time i disconnect my battery????

Could you come back to me as soon as possible please as this problem is rather annoying

Thanks