Airpods can not connect to macbook air

My Airpods suddenly stopped connecting to my mac. I have the first generation of the airpods, (bought 1,5 years ago) and ,my mac is a macbook air from 2014. It have not had any problem connecting until this autumn. Whenever i try to connect to my mac, it says that its connected but is still shearching. :

Then after some time It says that the connecting failed. the i have the option to either press an option button or connect. :

When i press the connect button the same thing happens again. If i press the options button this message popps up: (translated from norwegian to english: fill in the code that is shown on "Airpods", to connect to this mac.

Look up the documentation that came with the bluetooth-device, if you dont know the code oh have connection problems.

Which code is this popup devise talking about? And how can i get this code if i have lost my packaging box that the airpods came in?