Hi Shyam,
Ok no problem. Please follow these steps to reset you sandbox.
1) To be able to reset your sandbox you should switch from your sandbox environment to your production Environment. To do so:
Click on the Dynamics 365 on the top left corner, then click on All Apps on the bottom left corner and select Business Central(the one without sandbox as subtitle) --> this is your production environment.
2) now with the search, look for Sandbox Environment and click on the link as illustrated in the image bellow.
3) Then, on the page that popped-out, click on the Reset button.
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Don't hesitate if If you need more details or explanations.
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Best Regards,
