largo battery round wrong way ?

Hi i have done some thing really stupid i have put the battery on my brothers largo the wrong way round and have broke some thing not sure ill start from the beginning i put the battery on charge over night put the battery back on the wrong way tryed starting it realized it was on the wrong way put it on the RIGHT way and now i have no go light as its a diesel the head lights work and the a/c works But i have NO INDICATORS OR HORN or stereo PLEASE SOME ONE HELP ME would be so grateful also the car still turns over but does not start have checked all fuses that i can see under hood and in car plz plz help

kyle
October 2011