Substitute for Accent Seasoning
Accent seasoning seems to be mostly Monosodium Glutamate (MSG). You can try to find another MSG-type seasoning in your normal store (I don't know what brands might be available where you are so just look for things with MSG as the main ingredient), find pure MSG which is sometimes available in Asian grocery stores, or you could just add a cube of bouillon or two to help round out the flavour a bit. 

MSG basically tastes a little salty and helps make the flavour fuller or more intense. Bouillon does the same thing, so it would be an acceptable substitute in most dishes.