The attacking midfielder has been frozen out at Goodison Park after turning down a new contract.
Although Barkley, who surprisingly turned down a deadline-day move to Chelsea, is considered unlikely to play for the Toffees again under Ronald Koeman, his former coach believes that his long-term career prospects are bright.
"Ross has been through so much adversity already in his career," Martinez told talkSPORT.
"He went on loan to Leeds and Sheffield Wednesday and didn't play in those spells as often as he should have done. He broke his leg in an earlier period. He always overcame any adversity that came his way.
"This is a tough period for him now, and with the injury, but he is the type of footballer that will never give up. He loves the game and I can see Ross Barkley coming back and showing the real talent that he has."
Barkley was also linked with Tottenham Hotspur and Arsenal before the summer transfer window closed.