what is wrong with my dead rover 214i?

have no power whatsoever no alarm no lights no sound NOTHING have changed battery worked for a little while but made whinning sound when iwent to try again after afew hours it was completly dead again no sound when turning key or anything there has been no battery light on when it was running and have been told there would have been if it was alternator dont no what to do and cant take it to garage as its dead