Fact: If you can not log in to the router with the default username/password, then you have not reset it correctly. There is no way that your ISP put the actual router with factory settings on a non-standard login. The SSID could stay the same though after factory reset, unlike the login info. Is there not an online application btw for you to log in to your customer information on the web? Some ISPs have the router setting available in these kind of pages for you to access easily, and also the employees of the tech center if you call. This would also be where the SSID is saved.
The setup you tried is silly, not needed. The way you typed it, it looks like you unplugged it, and them push reset? Hope you did not hold reset for 20 seconds, release it, then take off the power and leave it off for 10 seconds for the info to go off your ISPs network. Replug and use the default gateway with default username/pass. This with a ethernet cable directly on the router. Use a fixed IP on your local area connection to be found in the manual, usually number between 1 and 50 after the default gateway range. Some routers will use the IP that was given to you if you make changes to your router by wireless connection, so it would not be able to save.