Is there anything besides implants to replace molars that have been removed? Have two back molars that needed to be removed, do not qualifie for implant due to my bone density. Is there anything else that I can do? Is there any type of retainer that can

Partial denture. A retainer for this situation is usually considered a short term solution, but still appropriate, and sometimes a required step of a larger treatment plan to restore your bite. In this case it is called an interim partial denture and is much like a retainer which includes the two teeth. A more permanent version of this would be called a partial denture, and is usually made with metal.
If . If implants or a bridge is not possible (a bridge wouldn't be possible in your case if they're going to take out the two furthest back molars) then you can consider a removable partial denture (rpd). There are two main kinds of partial dentures. The first one is called a "flipper" and is made of pink acrylic (plastic-like material) and has clasps that encricle some of your remaining teeth. A flipper is usually not the best option to replace molars that have no teeth behind it to clasp on to. In your case (which I am just speculating because i haven't seen your teeth) it sounds as though a metal-based rpd would be best. This has a metal skeleton for support and has pink acrylic over it. This kind of rpd is a lot more stable and durable than a flipper and can usually replace the furthest teeth in the back (when it does this it's called a distal extension rpd). In order for your dentist to make you an rpd, there might be some fillings or crowns they'll need to do first and if you have a lot of gum disease they might try and think of another option as your remaining teeth need to be stable in order to withstand the forces of a partial denture.