2
Log in to your site via FTP & navigate to /home/modules/ipboard/Skin/s1/
& overwrite all the skin files with those in your original IBF pagkage.
IBF for XOOPS has some heavily modified Skin templates... you cannot simply install a new IBF skin as you would if running standalone IPB - you have to go in & edit the skin files manually, 1 by 1... & if editing the profile page, don't even try to edit that one via your IBF CP, from experience, it will mess everything up. Download the Skin/Profile.php file directly, make your changes & overwrite it...
If the solution above doesnt return your forum to functional... if you see another folder in your Skin directory, navigate to within that & overwrite those files with the ones in your IBF package too.
Hope this helps.