My Logitech keyboard not working?

So I had this keyboard for a while now. It's a Logitech Wave 2.4 keyboard, I think. And for the time that I had it, it worked perfectly fine. But now it's acting all wierd. When I tried to type, the letters weren't showing up. And yes, it was on. Then I noticed the part where the light in the shape of a battery bar is was blinking, instead of just lighting on and staying that way. I changed the batteries multiple times, but it still didn't work. Does anybody know why my keyboard is acting that way? I'd really appreciate it.