How do I loose 20 lbs in 3 months?

I’m 25 years old and my weight has always been around 130-140 and I was happy with that.

I just weight myself this morning and I was 159 lbs. I can’t even use my own jeans/pants.

I would like some tips/suggestions on what I can do to loose 20 lbs by the end of Sept.

I will be getting married this year and I love my dress but it’s tight and it doesn’t look the way I wanted it to look on me. I feel like it makes me look older and my family members say the same.

I really need to loose it.

Will it even be possible?

If you have done that, please share your story.

Thank you :)