It's their money. If you're wanting a pile of new unnecessary things, I can see why they would say no. And you're 21? What the f*ck?
Tell them you will do some extra chores around the house to help out. Reasonably negotiate with them. Advise them you will help out with the work that is involved, like painting and organizing everything. Start by organizing all your clothes and personal items and show them that you want to make a change. They might be more likely to help you when you show them that it is something you are serious about.How to convince my parents not to make me take the bus?
Or if you have any savings or anything, you could offer to pay a percentage of what it costs to get your room done. Or yeah....chores and stuff...I had to pay £300 (half of what it cost to re do my room) which sucked ass but it was well worth it! xHow can I convince my parents to let me go to a gathering?