A cabinet drawer suffers lots of abuse. People slam drawers and little kids pull up on them. Occasionally, a drawer front will come off. Fixing it is easy.
Drawer fronts are attached from the inside of the drawer. Some are screwed in, some are stapled, and some are glued. For the repair, I would plan on screwing from inside of the drawer box and into the drawer front.
The big challenge is getting the front back on the drawer so that it aligns with the neighboring drawers. This isn’t difficult, and you should be able to use the marks on the back of the drawer front as a guide. Place the drawer front face down on a padded surface and set the drawer on top of it. You should be able to tell exactly where the drawer was attached to the front due to screw or staple holes, or even wear marks. Use some padded C-clamps to hold the front to the drawer. At this point you can place the drawer back into the opening but it won’t close due to the C-clamps. Make sure everything is lined up and then you can pre-drill some holes from inside the drawer to the front.  Make very sure you don’t penetrate the drawer front with the drill bit.
Once you have the holes drilled, screw the drawer box to the front and reinstall it onto the guides.