Usb modem to ethernet router?? PLEASE HELP!!!?

Our Modem has two ways to set up- Ethernet or usb. Unfortunately, the prongs to the Ethernet are broken and I now have to resort to using the usb port, which hooks directly into my desk top computer. The only problem with this, is I desperately need to find a way to get my wireless router, hooked up to the internet, which is only Ethernet compatible. I have tried creating a bridge (hooking my router to the computer through Ethernet) and hooking the modem up through USB. This, however, just leaves me completely without internet. I have read somewhere, that I need to give my computer an IP address to make it act as if it is actually the modem. I don't know if that will work and I'm really looking for somebody, who can explain it to me in layman's terms, as I am not a computer genius. If anybody could help me, I would really appreciate it. Trying not to resort to pocketing out a bunch of money so that I can have internet through my home network. Also, my modem requires installation with the USB port, so buying a USB to Ethernet converter will do me not to me any good, as the router has no way of installing the hardware.