Try an internet search for "bonsai gallery" and you might be able to pin it down from pics. Or better yet post a picture here and someone my be able to ID it.

Usually a watering problem will cause the leaves to dry and curl before they fall off. Your tree may be deciduous which means it will lose it;s leaves every winter naturally. Most deciduous trees are strictly for outside though. The cool weather gives them a rest before the heavy growth in spring.

Tony