You should try Facebook (to see if she has a page). There are also groups on Facebook, such as "Search Squad" which helps to find people. There are a lot of paid data bases ("Been Verified" is one that I can think of) that the search folks use. Also try Ancestry.com to see if she has a tree or appears on someone else's. You can often times track from there. Did you try "Whitepages.com" to see if there is actually a telephone listing? Sometimes the local library in the town you are searching in has city directories, phone books, etc. If it is a small town, sometimes calling town hall can get you a lead. (Tax records are public).
Let me know if you need anymore help. Good luck!