Firstly in most cases the main ELCB (Earth leakage circuit breaker) will cut power to most circuits in your property unless on a split consumer unit. It should certainly cut power to the sockets. My advice when this happens is always to switch off all mcb (minature circuit breakers) that are fed via the elcb, this makes it easier to reset the elcb. When this is done switch back on all the mcb'c back on one at a time. Have you checked to see if all the mcb's are back on? Normally sockets are protected via a 32A mcb or fuse this may be tripped that inturn took out the elcb
I am assuming your circuits are individually protected by mcb's and not fuses? How is the socket circuit protected? I am assuming all other circuits work ok after resetting the elcb?
:edit: if the circuit breaker to the sockets is tripped then i would not use the hoover again and get it checked over by a qualified electrician.