It just stopped working - without any smoke or
if the motor get over heated it will just switch off on you, let it cool down and try it again later,,,
there is also a thermal fuse inside the motor if this has poped on you then its a bust bin job im sorry to say,, there is realy not an easy way to fix this bit, and if you try by-passing this fuse,,,
it is a bit naughty!!! it could be just the brushes worn out on you but again getting them put in would work out cheeper to buy a new cleaner,
look at it this way,,, how old is it? how much work has it done for you? lots of years??????
maybe its time to put it out to grass