Try not to panic, she could have been busy or phone broken or who knows what- I know it is easier said than done though. Remeber that you spoke to her a couple of weeks ago and she was asking details for where to meet you so she is clearly planning to get to you on your big day.
Have a think about a plan B just incase. Although I strongly believe everything will be ok it may help you to feel less panicky. Think about who out of your friends is good at doing makeup. There will also be a hairdresser somewhere who can fit you in last minute for a hair up or blow-dry, you'll be ok. Remember that if your makeup or hair isnt how you planned it, no1 will know any different. Even though you probably won't need the plan B you might feel better knowing that it would turn out ok if for any reason she couldn't make it.
I'm keeping my fingers crosssed for you. Let us know if she gets back to you so we can breathe a sigh of relief!

Username courtersy of Missus S. Previously MrsH2014.
All you need is love...... and cake