Header gone?!

[Matt]

Oh yeah, that's a point, reverting it to default will revert it to the MyBB default, not the Afresh default.

[Mr. Lu]

Either you didn't expand it, or the template hasn't been modified by you (i just checked an unedited template and it didn't show the revert option, in the default theme).
So you most likely will have to install a new copy of Afresh Sky (no need to upload images, just the xml file and name it differently), then copy the code out of the header template and paste it to your original theme.

That should fix it.

It worked! THANKS!