Rev Counter, Cd Player And Batterie Trouble :(

[sofilinsk]

Hello to anyone reading this!

Firstly i bought my puma 3 days ago! it is a y reg and so a 2001 plate. The guy i bought it from said it has been sitting around for 2 months and although i drove it around for two days, yesterday i pulled up and when i got back in the car it wouldnt turn over at all. when trying the ignition the car speedometer, revometer and all other dashboard lights just flickered and i couldnt use my hazards horn etc? i figured it was the batterie and so went and bought a new one which seems to of done the trick? im just a little scared as people keep telling me it could of been the altonator? but i have no lights on on the dash now and it is running ok?? However since disconecting the bat my cd player has now locked and although i have a code of it when i put it in and hit the 5 key to enter...it locks it? plus i have now realised the revometer will not rise? is this a big problem? any advise would be brill as im a 23 year old girl how knows sweet F A about cars.