I'm not sure how new you are, so this is written with the assumption that you are very.
I'm not at my desktop right now, so I can't screenshot it, but the only explanation is that you accidentally turned render visibility off on your model.
Although there is another possibility involving layers, you'd have to intentionally have gone in and added it, so I'm going to assume that's not the case.
In the object manager (the list of shit in your scene off to the right on a default layout), your model, and each model in the scene as well, should have two circles next to it.
The topmost one will either be green(on) or gray(default, which is on). The top circle indicates if your object is visible in the viewport or not.
The bottom one is render visibility, it's MOST LIKELY red. Simply click it to gray or green, and your model will show up in a render.
If it's already gray or green, you've got something else going on. Post your object manager if this is the case.