You an restart Punchh on the Squirrel POS system by following these steps:
Navigate to Control Panel
Select >> Administrative Tools
Select >> Services
Select >> Punchh app (there should only be one app called Punchh there).
Check to see if the word 'Started' next to it.
If not, the word "started" is not there -- that is the problem. For some reason, the Punchh app has stopped.
To restart it, just right-click it and click on the Start command.
That should restart the Punchh app and your bar codes should print again.