Corsa-B.uk - Vauxhall, Opel and Holden Corsa B Owners Club

last week the fan belt snapped/fell of so i replaced the belt with a new one , but now when i leave my car overnight it wont start in the morning, once i have jump started the car it works and can drive but when its running,i turn on my lights and the clock display turns of :/ i disconnected one of the terminals on the battery and when i touch it onto the battery it sparks, im not sure what the problem is could it be the alternator or electrical problem......?