Removed the key the fan stay on suddenly off the fan

My radiator fan has stopped working. I just done a 157 mile trip and stop at a shop tgen restarted my journey and I heard a clunking noise. I stopped at my destination and looked under the bonnet and relised the fan was not going round...

Any help or advise please

Ok have replaced compressor cleaned and regassed system clutch and fan wouldn't run replaced fan relay it would appear there is a wire from ecm to clutch relay that supplies and earth i ran wire from battery to relay and all seem to work but i think the ecm montiors temp in car head pressure and switches compresser clutch on /off to suit. How do i activate it or is ecm faultly any help greatfully accepted thankyou in advance