Power of attorney to sell property by my brothers without my consent

You have stated that your siblings have left your share i.e., not sold, if so, what is your dispute.?

File civil suit for partition of property  and claim your share and possession  also pray for injunction and get restrained  your siblings not to sale the property till the partition arrived.

If the property is not partitioned and distributed then you can file suit for Partition, your siblings cannot sell the property without the property being partitioned and demarcated

If your brothers and sister sell  undivided share the prospective buyer cannot take possession of any specific part of the property unless the same is partitioned. Nothing stops your brothers and sister from selling their shares of property but the buyer will have to file a suit for partition to get the possession.