Perhaps this link can help you Conbee2 stick cannot be replaced with another one - #3 by manup
thank @Smanar , I will try this too (probably next monday this weekend I will be busy), but I don’t want to use my old backup. I’m ready to start from scratch.
I’ve tried also to reset some lights (Switch it OFF and back ON 6 times ) in order to connet to the raspbee… but it does not work anyway 
Can be from something broken in the network setting, but strange you have no error in logs about that.
Can install deconz on a desktop OS, on a PC machine for exemple, and compare your setting with the ones here https://github.com/dresden-elektronik/deconz-rest-plugin/wiki/Network-lost-and-configuration-restore-does-not-help (the last capture)
The network setting is written on the key, so you can move it on different OS.