The situation like this — where you had it working, put it away for some time and then get it out again but you can’t connect — almost always turns out to be a cable issue.
I would suggest that you disconnect the EggBot from both power and USB. Restart your computer, and then try connecting by USB alone. Leave the power cord disconnected until you’re able to establish communication.
Try different USB cables, if you have them available. If you are using any kind of USB adapter, also try connecting directly instead, or with a different adapter.