MonKENy - did you try holding the Reset button down for 30 seconds while the router is plugged in/powered up? That should put it back to factory settings. So, if someone (whoever brought it to you) manually configured the network settings and disabled the DHCP server (which is what it sounds like from your descriptions), it would wipe those settings and put it back to factory defaults which should be a 192.168.1.0/24 network, 192.168.1.1 address for the router, etc.
