Hello,
I mean a kind of a lottery that I can run for our guild members - I found an addon that used to be able to do this where members could buy lottery tickets - but this is not working anymore!
It is just to arrange some fun for our members - and say if members buy a lottery ticket for 1 gold then each week there will be a winner that recieves the price.
Does this explain it better ?
Yep. You are talking about the later of my descriptions. I'd have to look. Not sure that I have seen anything like this and if your talking about WoW then you might be out of luck as Blizzard has done everything it can to discourage and ban those that are participating in any kind of in game Gambling whether for real or game money.
A really simple way to do this with no mod would be to have each player in the guild but a number between 1 and x (depending on the size of the guild x would be the upper cap). All the players would need to do is send you an in game mail with the number they want before a certain date. It would be up to you if you allow any duplication of numbers or require each person to pick their own. Obviously this means you would have to track the numbers off line in excel or something and if you wanted unique numbers you would have to return the mail to the person and them understand that they number they picked was already taken. Then on what ever given day of the week you can just do a /random x (x being the limit you picked) then look at your sheet and see who one. Notify the lucky winner and send them their gold.