Why is the Xbox Controller not connecting to the PC?

Everything worked without any problems via the wireless adapter until I had connected the controller to my mobile phone for a short period of time and now it no longer connects to the PC

Did you re-pair it using the little button on the back of the controller?

There's such a button on the charging port. It is there to pair a device again, press the times

Switch off and pair your mobile phone

Yes, but now it works again anyway

Great then it's done