Hi, I'm Mike and I'll be glad to assist you. If you are sure there are no other GFCI devices, you need to check the connection in the 2 mentioned. You may have lost a connection on the Load connections. Another possibility is that an other outlet protected from the same GFCI has a bad connection causing the failure of the 2 that are dead. Below is a procedure to locate that outlet without opening boxes.
Not sure what you mean by :check the connections" but both of the GFCI outlets in the garage that have reset buttons on them are working fine. I plugged an item into each of them & power is getting to the item.