I did the same thing yesterday! My hedge trimmer is a Qualcast 370. I undid the screw nearest the lead and removed the panel by levering it open with a small screwdriver. This exposed where the wire is connected to the trimmer. Making a note of which wire went to which terminal I disconnected the short broken end of the cable and connected the other end. I am in the UK and the mains plug had a 13 amp fuse which I replaced.
Andrew, August 2007