After Effect is not responding.

The explanation of boot option is as follows.

https://helpx.adobe.com/after-effects/using/preferences.html

Hey @Aurko Deb Roy, sorry to hear this is happening. If you can't click on any buttons in the dialog, then I would try trashing your preferences. Safe Mode will start up with a temporary set of fresh preferences, but if you can't get to that, I would try trashing your preferences. 

Mac: /Users/[YourUsername]/Library/Preferences/Adobe/After Effects/[VersionNumber]

Win: C:\Users\[YourUsername]\AppData\Roaming\Adobe\After Effects\[VersionNumber]

If you don't want to trash them completely, you can rename the folder with the version number, then startup AE. A new one will automatically get created.

Thanks,
- David, After Effects Engineering Team