Dear GolamImtiazManik
We, the GPS-Trace team, are developing an applications for personal GPS tracking Forguard, Ruhavik and Petovik.
Please write to us at support@gps-trace.com with the model and unit ID and link to this topic. We will check whether we have such a unit in our system and if so, we will be able to give a hint to which login / email it is registered.
If you are not using the GPS-Trace application, then it is best for you to contact the application developers directly regarding the issue of restoring access to your account.
You can also try using the command RCONF to find out your tracker settings.
You can find guide for you tracker on our site - https://gps-trace.com/en/devices/sinotrack-st-903#instructions