An attorney, bank, accountant or corporation can act as executor. There are things you can do to insure your wishes are met. Parties that take this responsibility take steps to be informed of your demise.
Unfortunately, a full answer also requires a full background of the story. In the situations such as you are explaining you should immediately seek the counsel of a capable attorney that practices in the area of family law. If you cannot afford an attorney, you should seek a social service organization in your area. This answer is general in nature and does not form an attorney client relationship.
As previously stated a lawyer; accountant or bank can serve as your executor. However, a bank might be willing to serve as your executor even though your estate seems small many local banks have excellent trust departments and since they are corporate entities they will not die or move away. We frequently recommend trust departments as executors if there are no relatives or friends who are willing and able to serve as executors.