His image shows two messages:
There is a message
ERROR:root:Couldn't open wallet.dat/main
It suggests that you should shut down Bitcoin if it is already running. I would use Windows Task Manager to see if bitcoin-qt, bitcoind etc. are running.Ctrl+Alt+Of the In Windows-10 you should open a menu from which you can select
task-manager] You can close those processes from the task manager if necessary.
As your screenshot shows a second attempt without this error, it appears Botcoin-qt OK closed and the command completed successfully.
WARNING:root:pycrypto or libssl not found, decryption may be slow
This is just a warning, it does not mean that the command will not work, just that it may take longer than normal.
The message suggests that pywallet will use slow internal crypto functions if it does not have access to a fast external library of crypto functions.
wallet.txt The file should show you the information you want to extract.