Respected Sir,
I am very sorry to hear about your brother's problems. The inferiority he is feeling could be a part of Depression but there are a lot of other possibilities that need to be ruled out. He would have a tough time getting a job too unless he regains his confidence. The ideal person to diagnose his problem would be a qualified psychiatrist who can also further tell you the treatment required after a detailed evaluation
Next Steps
Consult a qualified psychiatrist
Health Tips
Don't wait too long as if it is Depression it could get worse