When I lost a game, I would like to correct the mistake and start there with a computer, is that possible? Thanks.
You can use an analysis board to set up the position and then use that to play vs the computer, via the option there.
You can also do it from the chess.com phone app. From your list of completed games, select a game and use the back / forward button to get to the move you want to continue from. Then, go to options and select "Finish vs Computer". I don't think there's a way to do this method if you play through the website on a computer.
On a PC playing on chess.com, get to the move you want to start at and then see the little Bulls Eye (?) logo at bottom right with title "Practice vs Computer". It should open a new window using this board and URL chess.com/practice/custom and then you can move from there against the computer.
When I lost a game, I would like to correct the mistake and start there with a computer, is that possible? Thanks.