How do I go back to fapping to vanilla porn!?
No porn for two weeks, fap to vanilla, no porn a week more, fap to vanilla
Start with cosplay porn and then to your fetish porn and your building back to "normal" porn.
Dunno why you would wanna go back though, other than content drought in certain fetish doujinshis.
I don't have any specific advice to give but for me at some point I hit a peak of degeneracy and then went plummeting back down to where I only jerk off vanilla hentai, softcore porn, and Japanese gravure videos. Maybe it'll happen to you too eventually.
the more you fap to something, the more your brain is trained to like it
Go nofap and see if you get vanilla cravings or can go back to it. After weeks/month(s) of it if nothing changes give up, you're stuck with whatever fetishes you have.