I create upto 100 blocks in AI2 offline but when I return I see that there is no any blocks.
This is the App Inventor 2 Community. You might get a response if you ask your question on a Forum dedicated to the particular off line (non-MIT) version of App Inventor you are using.
Here is what this Community knows about offline versions. The chatter might help you figure this out https://community.appinventor.mit.edu/search?q=ai2%20offline
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You can also try AI2 Offline's Discussion to get help:
https://sourceforge.net/p/ai2offline/discussion/general
They also have a technical support system (ticket system)