How can I teach an 18 year old girl to ride again? (Not ridden since 7) How can I teach an 18 year old girl to ride a bicycle again after she has stopped riding at the age of 7 due to crashing into a tennis net and getting scared about cycling. She's 1.6 m (Approx 5' 3"). She's scared of getting on the bike and is scared of falling off. Finds it hard to balance.

How can I also get her over the fear of crashing on a bicycle?
I would go for the same way I taught my kids to ride. Take the pedals off and let her scoot around until she gets comfortable with the balancing part. Put the seat low enough so that she can touch flat footed. This will allow her to gain confidence and not worry about falling. Once the fear is gone, the rest should come reasonably quickly.