no default gateway, unidentified network

Alright, some background on the issue,
Me and my roommate recently tried movings isps. While doing it I wasn't paying attention for a minute and my roommate tried copying the Mac address in some option our router had. Suddenly we no longer had a default gateway.

Now here's where the problem gets a bit complicated, I can't check if other pcs can connect since the internet isn't set up fully yet, since we don't have a default gateway we can't enter the router webpage as well.

I have been searching for solutions and none of them worked, registry, flushdns, resetting winsock(netsh) and ipv4 and ipv6, inputting a network address which suddenly disappeared, I tried resseting the ipconfig but I couldn't(no valid address), setting IP and default gateway statically, and I found myself out of options.

So I'm turning to the board, what can I do to fix this problem.
Sorry if anything isn't clear, first post here.

The thing that basically happened with the MAC is that there is a button that just copies it, which worked fine, but there was some other button he pressed while I wasn't paying attention which according to him did something to copy the MAC. We have reset the router many times, reboot and hard resetting it did nothing so I am convinced the problem is something we accidentally changed in windows.

I've also found out while checking out some setting
that the ipv4 winsock server on the network doesn't have a a value in it.

Also a bit of clarification on the router setup: we used to have some crappy router(called Hotbox) that had a weak signal so my roommate PC which used WiFi got crappy signal. So we bridged into it a dlink DIR850l which improved the signal massively.

First, you don't need a default gateway to connect to the router. The default gateway is used when an address is outside your network. Google for your router's manual and see which is its default IP, usually it's 192.168.1.1

Now, to connect to that address, you need to manually set your NIC's IP to the same network, let's say 192.168.1.2 with 255.255.255.0 subnet mask. Then simply browse to 192.168.1.1 and you should be able to connect to your router's setup page.