Doors will not open
 

key will no longer open the car but will lock it when turned in door lock?

Do all 4 doors lock and unlock via button nr handbrake?
Is the light on the key working?

Behind the keyhole there is a unit that uses small cables to extend the locking mechanism down to the level of the actuator. Sounds like one of those cables has failed.

To get to it you need to take out the handle ... to take out the handle you need to take out the window ... fun fun fun ... but not too difficult.

There's one for a fiver on Ebay ;)

https://www.ebay.co.uk/itm/Rover-75-...YAAMXQMXRQ4wMP

all doors lock when central button is pressed. The drivers door lever cable has snapped but the drivers door locks with the key, the other doors don't lock.I no longer have a working key fob.