Ah yes, the frustration of dealing with insurance adjusters. Most of them are dealing with hundreds of files, and your case is just another file.
The best way to reach an adjuster who is not calling you back is to reach out to the adjuster's supervisor. That almost always works, and is your best option for reaching an unresponsive adjuster.
If your case is not in litigation, your file then does not get much attention from an insurance company. But, as soon as a lawsuit is filed, you will find that suddenly the adjuster takes you, and your case much more seriously. Once that occurs, you can expect to receive more responsiveness from the adjuster.