I have DS1302 rtc module. I've tested it about two weeks ago and it worked alright, but now it can't remember the time. What's wrong with it?
What does it remember? Have you checked the battery?
Time. Well, I tried to light a led with that coin cell battery.
What sort of battery, a CR2032 oe a rechargeable version? Have you tried another battery? And you say you tried to light a LED. You didn't say if you succeeded. And did you use a current-limiting resistor when you connected the LED to the battery? Does it work when Vcc is powered but not when running off the backup battery alone, or not at all.
In other words, more information please, so we don't have to play 20 questions.....