I've got one with the same problem. Most likely the charging capacitor has gone bad from non-use. It's a fairly common problem in P&S cameras. It involves a tear-down of the camera to get to the charging circuit, and then sourcing the proper capacitor. Not sure if it's something you want to do, and if not, it's really cost prohibitive getting a repair shop to fix it. You can always just use it in daylight, and make sure your subject is never back lighted. Or just look for a replacement, there are many more of this camera floating around. Just make sure the flash works first before buying one.
PF