I would suggest using the "IC Master" book. I have not used it recently, but a new one was published every year, and it was very useful. It was very expensive to purchase, as well, so you need to only look at it. Finding the manufacturer would be your first step.
And, indeed, what makes you think it has failed? What is it supposed to do? Also, replacing such an IC without the needed resources is inviting a major failure. Removing one without damaging the PCB is hard enough, installing the replacement is also a big deal without the right tools.
If you can not even read the part number on the top, all we can tell you is the PCB package. If you can find the components around it, draw a basic circuit of what its connected to or give us the device part number, we might be able to help.