A locked workspace means billing, not data loss.
Why it happens
A payment failed and collection did not succeed. While it is still being retried, your plan stays live.
The plan or trial lapsed, or was cancelled and its period ended.
You downgraded and this workspace is above the number your new plan includes. On a downgrade, extra workspaces lock rather than being deleted, and the product picks which stay open by your plan's limit.
Nothing in it is deleted
Your chats, docs, creator lists, Collections, brand and voice are all still there. Locking closes the door, it does not empty the room.
Getting it back
Settings, then Billing. Choose a plan again, or move to one that includes this workspace. There is no second trial: the plan you choose is charged that day.
It opens again as soon as billing is current. There is no support ticket needed and nothing to restore.
If you are not sure which problem it is
The message tells you.
An ended plan or trial fills every page except Settings with Your plan has ended or Your trial has ended, and chat replies Your plan has ended. Choose a plan to keep chatting.
A workspace locked by a downgrade says Workspace locked in the sidebar.
If it says none of those clearly, send us a screenshot and the workspace name.
Your other workspaces
After a downgrade, only the workspaces above your limit lock. The ones your plan covers keep working, and you can switch to them in the sidebar. When a plan or trial ends, every workspace locks.