Here are a few tips - give your toddler a safe place to practice. An ideal case would be a three step stairs with banister to hold onto while climbing. - now give him/her time to practice, with vigilance from vicinity. - keep increasing the difficulty and let your child explore without your help (best incentive is when you are upstairs and they follow you).
On top of what Harshit has recommended, I think lots of encouragement works as well. Praise her tremendously if you see her doing it on her own and I think that will gives her the courage to attempt it again. I am sure with this, she is able to manage on her own soon.
in addition to what the others recommend, try keeping a much loved toy at the top/bottom of the stairs. Mummy could stand at the top and daddy at the bottom to cheer her on too.
thanks