So, I guess what we're looking for should be a not-too-tight onahole with lots of different stimulation.. I'd recommend even using two very different onaholes, so you don't "condition" your penis to a single one. And for you to enjoy sex again, it shouldn't be "lifelike", so you're exposed to a good variation of sensations.
A few ideas:
http://blog.onahole.eu/bangee-shake.htmlhttp://blog.onahole.eu/ju-c.htmlhttp://blog.onahole.eu/eroman.htmlhttp://blog.onahole.eu/virgin-age-graduation.htmlhttp://blog.onahole.eu/age-series-twenty.html{ La Bocca Della Verità }
How that would be, Bangee Shake (mild and unconventional) and Ju-C (intense without being tight or lifelike)…
Also: masturbate once or twice per week, and make yourself cum just once :) Remember the brain is the main sexual organ, if you don't enjoy sexual activity then that means your desire is low. Fantasies, pheromones, hormones and what could be a "mating season" pattern for humans come into play. Many stuff can kill the desire: stress, mood, lack of sleep, unhealthy food, performance-quest in sex, too much porn, "quickies",…
Tell us how it goes :)