Advent 5303 battery not charging?

After not using the machine for 6 months there is no charge in the battery and it will not charge. Icon says "0% available(plugged in not charging)" I had this same problem when I first bought the machine 2 years ago and I was able to find a simple solution that worked on one of the forums. Unfortunately I can't find it again and have now forgotten what it was. I would be very grateful if someone out there could help.