I want to lose 85lb but I don't know how to do it some. help please!

I am 19 years old and 5'6 and I am 235lbs. I used to play basketball but I can't anymore because of my knee and ankle. I want guys to like me. I don't like looking this way. I say I will try something and then I end up not doing it. I want to be down to a size 7or8. Anyone have any ideas?
I want to lose 85lb but I don't know how to do it some. help please!
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