Which keys? Is it always the same ones? Does the keyboard work better on other machines? Do they work if you, say, press harder or wiggle them around a bit? Have you even tried unplugging and reconnecting it, or rebooting the computer, yet? What machine are you using this with? Have you tried any other keyboards, or indeed other USB devices,w ith that machine? If it has multiple USB ports, have you tried switching to a different one? Is the cable damaged in any way? Was anything spilled on the keyboard? What style of keyboard is it (no, I'm not going to research this for you, you're the one trying to get *us* to spend our time helping *you*)? Has it ever had problems before? How long have you been using it? Have you searched the Internet for anybody else with this problem?
I don't know what the solution is, but I can tell you the first problem you need to solve: you write crummy bug reports / requests for help. Your entire post boils down to
"It doesn't work. Tell me how to fix it"
and I was sorely tempted to respond with a simple "No." because you've given me absolutely nothing to work with, here.