My printer has gone nuts!

Oh dear- all was going well until I had to strip and clean the extruder nozzle. When I refitted it and started a new print, my K8200 drove the nozzle down onto the bed. I found the emergency stop to be rather slow in acting. Once things stopped and I raised the nozzle, I found that none of the limit switches worked anymore. Also in manual mode the x and y axels are reversed.

Do I need to reinstall the software? Do I need to do the same for the drivers? If so, can someone remind me where the downloads are?