I'm 25 and have never had sex, never touched a girl in any meaningful way.
I bet you're not the only one on this forum that hadn't by that age, but I can't be sure. I obviously had sex before that age (considering I'm 22 and pregnant), but they say it's easier for girls to get laid than for guys. Also... in case you hadn't noticed, a lot of guys on this forum just don't notice it when a girl is interested in them, and hence miss a lot of opportunities. So you might in reality be super attractive but just never have noticed it. 
Yet another reason to hate myself and cite my inferiority.
My list of failures has no end.
You could take the positive approach and just say that you're saving yourself for the right person, instead of being a *** (m/f) like so many other people.
And in case you hadn't noticed yet, tons of people haven't found the right person yet by age 25, so you're not behind on that one yet. 
If you were willing to sleep with just anyone, I can assure you that it shouldn't be that hard to find some girl that's desperate. I recommend against it though.
I hate when people talk about having sex; if I can't have it, why should they?
It's a part of life... and vastly overrated in western society. I'll admit it feels good, but imo it's definitely not worth the effort and risk to just go have sex with someone you don't know all that well. Talking to girls and reading stuff I've found that most had a rather lousy first time and plenty of lousy other times too...
But along the same lines, one could argue that people should keep their mouths shut about just about any topic... I don't have money so don't mention money... I don't have a college degree so don't mention college... on and on. There aren't many people on this planet that have everything... pretty much everybody is lacking something in their lives, and often more than one thing. You happen to be lacking a gf and a sex life. Accept it... it's not likely to be a permanent lack anyway.