Watch the online videos for freshman/sophomore CS courses and do the homework/projects (very important) from the corresponding textbook/course. Plenty of optio

Watch the online videos for freshman/sophomore CS courses and do the homework/projects (very important) from the corresponding textbook/course. Plenty of options exist: MIT OCW, etc. If you have enough willpower to do that (and most people won't no matter how strong their regrets are), only then consider going back to college and even then a reputable online program would probably be your best bet.