I have to reset the radio in my Nissan xtrail. I have the code and have put that in . The last number keeps flashing and the radio still doesn't work

Not sure if you've reset it before but here are the directions. Pay attention to last paragraph.
If you have done this sorry for not having another answer.
The trick is to know that only the channel preset button labeled 1,2,3,4 are used to enter the PIN - each channel button is used to increment the value of one digit on the display. Channel preset '1' increments the first digit, '2' the second, and so on. Each press of a channel button increments the corresponding digit by one, cycling back to 0 and around again.

So to enter 1924 as a PIN, you'd start with the display reading '0000' and press
- preset 1 once (increment 0 -> 1)
- preset 2 nine times (increment 0 -> 9)
- preset 3 twice (increment 0 -> 2)
- preset 4 four times (increment 0 -> 4)

The last one's easy, as the radio unlocks as soon as you hit the right code so you just keep pressing preset button 4 'til it unlocks! (i.e. it's a 4 digit PIN but only as secure as a 3 digit one.