The good news is that this has been discussed before.
The bad news is that you didn't reveal if you backed up your EFS credentials.
And more good news. If you didn't then
http://www.lostpassword.com has a tool to let you regain access to those files.
This is often where folk stop using EFS.
As my system was not booting, I re-installed my xp version 2002 SP3 on the same drive in the folder winxp. After installation I moved all documents (all are encrypted) present in older user to present desktop. It had few folders, office 2003 files & many office 2007 files. After installation of all the drivers, I installed Tune Up utilities. In that I got a message to disable data access on network and disabled it. From then I m unable to open any of the files on my desktop or copy them to other location. But still I can open/copy all other files except my desktop. Those files are very important for me. How to get back my files? Please help me.