If you can't find her will, that could be a problem. You will need the original signed will to be admitted to probate. The insurance policies are less of a problem, because she will get mail from the insurance companies at least once a year, so eventually you will know what companies there are; and if the policies cannot be found you can sign a lost policy affidavit, It would be advisable to fill the gap about the living will and the health care power of attorney with an attorney, because otherwise she may have a document stuck under her nose at a hospital when she is there in a possible emergency, and neither you nor she will have time to think and discuss the document, or the options that she may have with those documents. Signing those documents in an emergency room is not the best time to consider them.
You have a couple of issues here. First of all you need to have authority to act for your mother if she is not able to with regard to her financial and health care decisions. If there is no power of attorney you may need to have a guardian appointed.
With regard to what happens should she pass away if you cannot locate her will or a copy (you can probate a copy of a lost will) then the state statue will determine who receives her assets. In general the assets will pass to her spouse if any then to her children in equal shares.
I would definitely consult an attorney as soon as possible.