Electrical Problems - 02 Corsa SXI 1.7 Diesel?

Hi,
I have an 02 Plate Corsa. The battery recently went flat and i seem to have been left with loads of electrical problems. The passenger side electric window has stopped working, the indicator only seems to work when it feels like it (passenger side), petrol gauge no longer works and the radio wont turn on.

I have taken it to a car electrics mechanic but he only addressed the Radio issue and said i may need a new ignition line putting in to the radio?

Any input would be greatly appreciated.

Thanks
Richard