A guardian can sell a minor's property only for legal necessity. Ie : for meeting the educattional expenses of the minor ..etc
However if the guardian has sold the minor's property , the sale can be set aside after the minor becomes a major.
The Period of limitation of 3 yrs applies only if the minor upon reaching majority has failed to institute a suit .
So, you may file a suit for setting aside the sale , by giving valid reasons for the said cause of action.