Dentures crack, which is the reality of the prosthetic. Sooner or later you're going to have a crack in the denture, a tooth is going to fall out or something similar and inconvenient is going to happen. If you have acrylic dentures, you can use products on the market that allow you to repair your dentures yourself. Only use products that can be safely put in your mouth and will be effective on your dentures.
Clean the acrylic dentures and dry them before you attempt to bond them back together. Use gentle soap and water to clean the dentures, then rinse them thoroughly.
Apply your acrylic bonding to the crack in your dentures. If your tooth came out, put the bonding agent in the hollow hole, then put the tooth into it. Set the edges together and do not allow beading to occur from the acrylic bonding agent.
Hold the dentures in place until the bond has cured and it's completely dry.
Try out your dentures to see whether or not your repair work has fixed the dentures. If the repair doesn't work, then you can try again with a different bonding agent, or you can have the dentures professionally repaired or replaced at a higher cost if they're truly beyond home repair.