I can't find my little brothers Individual Taxpayer Identification Number, how can retrieve it.

If you are your brother's legal guardian, as listed on the original Form W-7 that was used to elicit the ITIN from the IRS, you can call the IRS ITIN Center at 1-800-908-9982.

Once you establish your identity with them, they will issue you a replacement ITIN letter. They MAY or MAY NOT tell you the ITIN over the phone.

Am already fill the application for itin numbers then I don't recive anithyng cause we switch a new address how can I found where is those numbers

See the phone number on my earlier post; call the ITIN Processing Center and ask for a replacement ITIN letter.