It's a mains operated hedge trimmer - you might have said but no matter.
The manual can be found here...
http://www.manualslib.com/manual/787248/Florabest-Fht-600-B2.html?page=12#manual
But the troubleshooting section does not mention your failure.
Clearly something in the gear train has failed - your choices are a self repair - a professional repair - or a new trimmer.
Spare parts my be difficult to obtain.
Good Luck...
May 2016