Lits flashing won't charge

I hav a compaq laptop all of a sudden it doesn't work with or without the battery.I brought. New charger and the on switch comes on as well as the battery chage lit and harddrive light but then wihin seconds they all flash and the computer stays off. Even took it to a shop in highstreet who replaced the recharge port,it still doesn't work.hey kept it for 5weeks an still had the cheek to charge me!! My dad died in june09 and this is all I have left of him.please help me.please email helenmarieprice@live.co.uk