Its possible that your son may be suffering from a mental issue from the war such as PTSD, depression or even a TBI.
People see things in war & don't feel like talking. Or, he may even have gotten hurt physically as well as mentally & don't feel like dealing with people at all. This is the case with alot of servicemembers that have been in war.
Give him time to heal. That may take a long time, but give him time.
If he does talk to you, do not 'burden' him with financial issues & problems in life. Most likely, he is dealing with enough on his plate. Many servicemembers have committed suicide since coming home. So, we do not want to add to his already many issues.
I hope things work out for you.
I will pray that you hear from him soon.