Windows 7: How to change my IP Address and Default Gateway

As far as I know, you would need default gateway access. Since he did say that it is not allowed to access the default gateway, access would require unethical methods. Since that is illegal as mentioned, default gateway access cannot be obtained legally, thus you wouldn't be able to change any IP configuration (Default Gateway Address + the IP assigned). I don't think manually changing your IP address will work, it would require the router to assign static addresses. You could try asking them if they could change it.

I think the internet provider will not allow me to do that or will ask extra fee for that.
About changing my ip and default gateway, is this how I will do it ?

Never mind, thank you so much guys for giving me ideas. I hunched a way on how to solve my problem and it worked. Thank you

That is forcing your computer to rely on given data, rather than requesting the router for a unique IP Address. Usually, manually assigning an IP address wouldn't work. It would simply not register to the ARP Table.

If you could tell us how you solved it (changed your IP address), that would be nice.

The guy who was asked to set-up our router inserted the main internet cable in the first port instead of inserting it in the "internet port" of the router. So, I tried it inserting there and it worked; no need of changing my ip address or whatever because after I plugged it and typed "ipconfig /all", the default gateway automatically changed to 192.168.1.1

I curse that guy for not setting my router properly

That means this guy plugged the modem into the LAN port on the router rather than the WAN port, hmmm that's not gunna work too well. No need to assign any IP's with a working router because with DHCP enabled it's all automatic.

It's too bad we can't see that sort of problem from here.