I have a Nissan Micra 09 reg.I put the code for my radio correctly but when I turn off the car and turn it back on the radio asks me to code in again can anyone help

You can get Blaupunkt radio codes for a small fee from this link:

https://www.gumtree.com/p/in-car-audio-gps/car-radio-codes./1370897099

Call the dealer & quote your Vin number

Sounds to me like either someone has had it out and it is wired incorrectly, or possibly a blown fuse, but you are loosing KAP when the key is turned off.

You need to be certain you are entering the correct code in the correct way to avoid being permanently locked out of the radio.

Different territories and models have slightly differing radios and the coding sequence can vary slightly. The vehicle literature pack should either contain an audio manual or the details will be found in the vehicle handbook.

You must have the radio repaired to enter the code, there is no way around the problem of the inoperable button. Next time use a battery back up, never completely power down the system. Walmart has these battery power supplies.

get correct manual from Nissan.
if stock radio,
the generic nissan, for 2011 will list all radios sold that year.
get one.
nissan dot com, its free.
online or at the parts counter.

Honda's have the code inside the drivers door frame. There is tire pressures and other data there as well.

You go to the dealer for the radio code

Why would you remove the radio ?

The dealer has your Vin # & shouldn't need any radio serial #

Sounds like a fuel issue if you have run it dry, maybe a blocked fuel filter, or maybe it needs new spark plugs, check the air filter as well.