The airways are blocked.
Switch the vacuum cleaner off using the On/Off foot switch.
Remove the mains plug from the socket.
Disassemble the floorhead, hose, handle and telescopic tube.
You can carefully push large items which are jammed in the hose or in the telescopic tube towards the floorhead using a long object (e.g. a broom handle).
Items causing a blockage are usually easy to shake out of the handle.