Why doesn't my key turn after battery been fully charge but alternator not repla

What is your question?

One day I got stranded n pull at auto zone try to get my alternator n battery tested out but they key wouldn't turn so the guy charge the battery for me n a soon I plug it back in the car crank up like none but a soon as I got home n turn if off now the key won't even turn or none can the alternator cause that to happen