How can I get my hedge trimmer blades to engage with the motor?

I purchase about 2 years ago from B&Q Northwich B&Q's own branded Hedge trimmer PR0600HTA Serial no 10495783. It has been used 3 days each year (9days in all) and now the motor runs but will not engage with the blades. Unfortunately I would have taken it back to B&Q but I have misplaced the receipt. Please help.