All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
If your brother has wronged you and prevented you from taking your right in inheritance as you stated in your question, then he is totally wrong. So we advise you to ask Allaah as much as possible to enable you to get your right back, then seek the help of righteous and pious people, and the help of those whom you think will influence him. If he gives you back your right, all perfect praise be to Allaah, but if he refuses to give you back your right, you can take the matter to one of the Islamic centres to study your case and remove the harm from you, or to the Muslim community who would act as a Muslim judge if the latter is not existent. In principle it is not permissible to be judged by man-made laws as Allaah says (which means): {Have you not seen those who claim to have believed in what was revealed to you, [O Muhammad ], and what was revealed before you? They wish to refer legislation to Taghut, [anything worshipped other than Allaah] while they were commanded to reject it; and Satan wishes to lead them far astray.}[Qur'an 4:60].
However, if one is forced to resort to man-made laws after exhausting all other permissible means, then it would be permissible to resort to them due to the necessity, provided that the Muslim would not take more than what he deserves. If these man-made laws give the Muslim more than what he deserves, it is not acceptable for him to take anything in excess of his right.
Lastly, it should be reminded that suing a brother or another relative in order to get one's rights back is neither considered as forbidden in Islamic Law nor as cutting relations with them.
Allaah knows best.