someone sending the legal notice i have not accepted what will happpen

Please accept it and take assistance of a lawyer. Not accepting it would amount to "refusal" and if the person sending it takes it to Court, it is likely that an Order may be passed against you. I recommend receiving it and then deciding how to reply to it with the assistance of a lawyer.

It depends on the Endorsement the Postman has made on the postal cover. If he has endorsed as 'Refused' or 'not claimed' the service of notice will be deemed sufficient and further action as contemplated under law will follow

If a legal notice is sent and if you refuse to accept the same there will be an endorsement to that effect on the postal cover which would deem to be served upon you. Incase of door lock, addressee left, it cannot be deemed to have been served.

I always recommend my clients to take all notices served on them personally, if they are in and around at time of service.
Per Law : refusal to accept notice is good service. that means you can expect next step /stage of litigation.
contact your lawyer immediately, sign Vakil patra and ask him to be observer, if needed he/she may file Vakilpatra at appropriate situation.

You need to accept any communication addressed to you. If it is a legal notice sent especially by an advocate it will have its own meaning. If a legal notice is rejected by you, in legal terms it means you have received it. Damages could be done with this presumption. Therefore, rejecting a legal notice is not a wise step. Receive it and reply it appropriately.