what can I do if i know their was a will but now it has mysteriously disappeared with in a day of her death

Depending on who the deceased person was with relation to you, and if you believe you know who has the Will, you may be able to petition the probate court to compel production of the Will. You may also be able to seek appointment as temporary administrator. However, also depending on who the deceased person was in relation to you and your brothers, and whether you and your brothers are beneficiaries in the Will,  you may not actually want that Will to show up. If a Will is witnessed and signed by persons who are beneficiaries under it, then the beneficiary/witnesses are generally allowed to serve as witnesses, but the benefits they would receive under the Will are automatically invalidated. So, if you were expecting the Will to benefit you, and you also witnessed it, you may find that the result of having that Will admitted to probate is that you don't get any benefit. If you really want to pursue whatever interest you may have in this estate, you really need to find an estate litigation attorney and get a consultation. The attorney will be able to get more information about the situation from you and can then give you some idea of what your options may be, and what pursuing those options is likely to involve. Best wishes to you.