I can't tell you what to do since I don't know
what you changed ... but for future reference:
If you compile a new kernel from the same
source, use the EXTRAVERSION = in the Makefile.
That way you can have the same kernel release,
but several module directories ...
To revert to your old settings... grab your slack CD,
go to your cdrom/slackware/k directory. Start mc
(midnight commander) and go to the kernel*.tgz you
installed. Highlight it with the cursor, hit enter, find
.config and copy it to your kernel source directory.