Hi I've just changed battery on car and lost radio now need code it's a Sony unit serial number is m920208 any help grateful

The Keycode for your radio should be: 5268

There's a big difference between m026143 and m920208.

Are we talking two radios?

No that was serial number in paper work I got with car tried code you gave me didn't work so managed to get stereo out of dashboard and it has this serial number on m026143 so it's either had a new stereo at some point before I bought the car or the radio booklet in my paper work is not for my car

The Keycode for your radio should be: 0793

It's actually quite common for the car's paperwork not to match the radio that's fitted so please don't worry about it! During a car's life radios fail and get changed and handbooks get mixed-up when cars are in dealerships. It happens!