Start by checking simple things - that all connectors are pushed on tightly, and no wires broken. Check all fuses too. The alternator isn't a separate unit, it's a winding within the motor. The regulator/rectifier is a little block with two or three connections that may be on the motor or under the dash area. If the connections are all good, the regulator/rectifier is the most likely problem. It can be damaged from jump starting and other things.