I seriously want my nose pierced and my mum hates piercings so she won't let me :(
I need some sort of way to convince her to let me have it done ! So if anyone could help me out with some idea's then that would be great ;)

Show her you're responsible enough to get one and to look after it properly. Tell her that you will pay for it yourself and if you don't earn money from working then just be helpful around the house, get good grades etc. if she still says no then I'm afraid you'll have to wait till you're 16 or 18 or however old it is..