Hi Sharjil,
Sorry to see you are having issues with your Octopus instance.
To get you back up and running I would look at this link below:
This should get you out of the state “All Octopus Server nodes in this cluster are draining tasks.”
In addition to this, you can do it from the command line using this as a guide:
Once you do that, it would fix this issue for you.
I look forward to your response once you have completed that.
Kind regards,
Ziaul