What Do I Do to inherit property of my brother.

You obtained the death certificate and legal heirship of your parents and brother? Then you can, better to consult a local lawyer and act accordingly 

You have to obtain a legal heir certificate also from a competent official like Tehsildar, get the properties mutated in your name after submitting the documents with the prescribed application.  You may have to file such prescribed fees.  Contacting a local advocate is a must in your case, as your brother himself is not having any title deeds or documents that state his ownership.

Yes you need to obtain legalheirs certificate and with it you can transfer the property to you name 

The property is already devolved upon you. Please note that inheritance takes place by operation of law. All that requires to be carried out is to get the mutation carried out in the Revenue/Municipal records. In this context, each State has its own procedure. Ascertain the procedure in vogue and take steps accordingly.

Alternate for mutation is to institute a suit for declaration and perpetual injunction.

Inheritance is governed by personal succession laws (Hindu / Muslim / Indian).

It is better to consult a local prudent lawyer for appreciation of facts/ documents and professional advise. 

What is the problem in getting mutation carried out? 

Since you are the lone survivor to survive your deceased brother, in the capacity of  his class II legal heirs (assuming you to be a Hindu by religion), you are entitled to succeed to his estates which he left behind upon his intestate death.

However the Tehsildar or the revenue department are not authorised to furnish class II legal heirship certificate.

Hence you may have to approach court with petition seeking succession certificate or a suit for declaration to declare you as his class II legal heir to succeed to his estates left behind upon his intestate death.

Once you get this suit decreed in your favor, you will be acquiring the title to the property and you may apply for mutation of the property to your name to prove your possession.

Any other step, if taken on any misguidance by people with half baked knowledge in your surrounding, may land you in more trouble and you may not find any remedy if the things become more complicated.

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