devstack is not for shutting down. When you reboot your server, it won't restart all OpenStack services and won't rebuild all storage. Only use devstack for testing, and only if you can keep it running. Alternatively, you can install it on a VM, which you hibernate (Virtualbox term: savestate) when you need to shut your computer down.

By the way, when I read "please help me asap", it sounds like you think I have an obligation to help you and comes across as rude. I know you don't mean it like that, but people might not be inclined to help you.