When I first meet with a new singer, I know they are probably going to be nervous. Some aren't, but most are. One of the first things I do is a little anatomy lesson, regarding the "singing instrument". It is a complex machine. There are also some things about it, which are simple. One simple thing is that the vocal folds (they used to be called vocal cords) have to vibrate in close enough proximity and not "fly open" and if they do this, your voice will not "crack" or "break". Cracking and/or breaking is caused by the inability to maintain the bringing together of them (it is called adduction). Many, if not most, people have a break in their tone quality, as they ascend from chest voice to head voice. It is not a lack of strength which causes the crack; it is a lack of coordination. It is usually caused by the larynx rising as the pitch ascends. Untrained muscles inside the larynx contract when the larynx is up, as it is when we swallow something. They are just doing what they normally do when the larynx is up. It works very well for swallowing, but not for singing. If we can make some sounds which use the sternohyoid and sternothyroid muscles, we can learn to use those and ultimately achieve laryngeal stability, so that the larynx does not rise as the pitch rises. What happens then? No more cracking and a lot more usable vocal range. Maybe (if you're VERY lucky), you have no crack in your range but you have other issues. There are solutions to those, too. A little knowledge and a lot of practice can take a person a long way. Some have made it to Broadway or to a record deal. Others have been on The Voice and other fun TV shows.
What else? Maybe you're a victim of some common and confusing myths about singing technique. We can clear up common misconceptions and get you onto a road which might lead you to a better place.