I have noticed some comments about dropbox. Your might be same as me: I had installed dropbox before SVN. Because of this dropbox's icons appeared in regedit first.
Anyways, i have tried many solutions with preferences, but none helped me out.
Solution which helped me i have found here: http://www.sitepoint.com/missing-tortoisesvn-file-status-overlay-icons/
The fix I’m about to describe involves tampering with the Windows registry. It’s dangerous and one false move could trash your Windows installation!
All you need to do is delete several regeedit values in this path: HKEY_LOCAL_MACHINESOFTWARE/Microsoft/Windows/CurrentVersion/Explorer/ShellIconOverlayIdentifiers
so it be in sum less or equals 11 values., else some of icons will be ignored.
In my case I had dropbox icons first, so I left first 3 ones and one which I don't know why it's for with name - EnhancedStorageShell.
After i removed values, Restarted windows. Done! Icons finally appeared.