Hello @kien
Welcome to the Atlassian community.
If you expand Spaces in the navigation panel and select More Spaces, then View All Spaces, can you find the space listed there?
Can you click the gear icon (in the upper right corner near your avatar) and select Spaces there? Then can you find the space in the list displayed?
Be advised that we are a user community. We are users of our own Jira instances. We don't have access to yours. We can ask questions and offer suggestions about debugging your issue, but we cannot examine your system or make changes to it ourselves.
If you want to work directly with Atlassian technical support on this issue you will need to create a support case in their customer portal:
https://support.atlassian.com/contact/#/
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