Follow this simple procedure to patch ur uxtheme.dll file

How to use this file:
1) Download the file and extract in a handy location (eg: your Desktop). This should create a new uxtheme.dll file in that location.
2) Go to C:WINDOWSSystem32 and rename uxtheme.dll to uxtheme.dll.old
3) Put the new uxtheme.dll into C:WINDOWSSystem32
4) If you get any warnings from Windows stating that an original system file has been replaced, you must click "Cancel", otherwise the new uxtheme.dll will be replaced with the original one.
5) Reboot

After this download any .theme or .msstyles file and run it

Download

Some great sites to look out for themes are :
www.deviantart.com
www.wincustomize.com
www.themexp.org