Most likely you’ll only get about 1/2 of what you paid. But if you used it for several vacations you can look at the time you spent there as time you would have paid to stay at resort hotels. You might have luck selling it through the Time Share Users’ Group website, www.tug.net
I think my husband (wasn't married to him at the time) said that he put flyers on car windows to sell his timeshare. It worked for him. The timeshare people weren't too happy with him, but I doubt they can do much.