Codes P0300 and P050B?

I changed the spot pleasant coils a few months ago. However, last week when I went to start the car and misfired. When I plugged in the OBD reader, it gave me a code of P0300 cylinder 6 misfire. So, I went and bought more expensive spark plugs thinking this might have been the issue with a faulty spark plug. I've got to replace it with the new spark plugs again. This time the car crank, just a little Dennis thought I'm making a weird like whining noise. I would like to start over timing, turning applaud the OBD reader again this time it gave me codes of all cylinder misfiring, and P050B coast start timing. What could have caused the maintenance? Always up to date, never had any issues. Not even any warnings before this happened.